Consolidate ChunkedIO

12 files changed, 427 insertions, 436 deletions

diff --git a/lib/gitlab/ci/trace/chunked_file/chunk_store/base.rb b/lib/gitlab/ci/trace/chunked_file/chunk_store/base.rb
index e2645918a40..6e104a6d764 100644
--- a/lib/gitlab/ci/trace/chunked_file/chunk_store/base.rb
+++ b/lib/gitlab/ci/trace/chunked_file/chunk_store/base.rb
@@ -22,18 +22,32 @@ module Gitlab
               raise NotImplementedError
             end
 
+            # Write data to chunk store. Always overwrite.
+            #
+            # @param [String] data
+            # @return [Fixnum] length of the data after writing
             def write!(data)
               raise NotImplementedError
             end
 
+            # Append data to chunk store
+            #
+            # @param [String] data
+            # @return [Fixnum] length of the appended
             def append!(data)
               raise NotImplementedError
             end
 
+            # Truncate data to chunk store
+            #
+            # @param [String] offset
             def truncate!(offset)
               raise NotImplementedError
             end
 
+            # Delete data from chunk store
+            #
+            # @param [String] offset
             def delete!
               raise NotImplementedError
             end
diff --git a/lib/gitlab/ci/trace/chunked_file/chunk_store/database.rb b/lib/gitlab/ci/trace/chunked_file/chunk_store/database.rb
index a7db214f428..3c2805e83f7 100644
--- a/lib/gitlab/ci/trace/chunked_file/chunk_store/database.rb
+++ b/lib/gitlab/ci/trace/chunked_file/chunk_store/database.rb
@@ -48,6 +48,8 @@ module Gitlab
             end
 
             def get
+              puts "#{self.class.name} - #{__callee__}: params[:chunk_index]: #{params[:chunk_index]}"
+
               job_trace_chunk.data
             end
 
@@ -56,9 +58,10 @@ module Gitlab
             end
 
             def write!(data)
+              raise NotImplementedError, 'Partial writing is not supported' unless params[:buffer_size] == data&.length
+              raise NotImplementedError, 'UPDATE (Overwriting data) is not supported' if job_trace_chunk.data
+
               puts "#{self.class.name} - #{__callee__}: data.length: #{data.length.inspect} params[:chunk_index]: #{params[:chunk_index]}"
-              raise NotImplementedError, 'Partial write is not supported' unless params[:buffer_size] == data&.length
-              raise NotImplementedError, 'UPDATE is not supported' if job_trace_chunk.data
 
               job_trace_chunk.data = data
               job_trace_chunk.save!
@@ -75,7 +78,10 @@ module Gitlab
             end
 
             def delete!
+              raise ActiveRecord::RecordNotFound, 'Could not find deletable record' unless job_trace_chunk.persisted?
+
               puts "#{self.class.name} - #{__callee__}: params[:chunk_index]: #{params[:chunk_index]}"
+
               job_trace_chunk.destroy!
             end
           end
diff --git a/lib/gitlab/ci/trace/chunked_file/chunk_store/redis.rb b/lib/gitlab/ci/trace/chunked_file/chunk_store/redis.rb
index cb45cd5fba5..c87275319d9 100644
--- a/lib/gitlab/ci/trace/chunked_file/chunk_store/redis.rb
+++ b/lib/gitlab/ci/trace/chunked_file/chunk_store/redis.rb
@@ -51,6 +51,9 @@ module Gitlab
               end
             end
 
+            BufferKeyNotFoundError = Class.new(StandardError)
+            WriteError = Class.new(StandardError)
+
             attr_reader :buffer_key
 
             def initialize(buffer_key, **params)
@@ -64,6 +67,8 @@ module Gitlab
             end
 
             def get
+              puts "#{self.class.name} - #{__callee__}: params[:chunk_index]: #{params[:chunk_index]}"
+
               Gitlab::Redis::Cache.with do |redis|
                 redis.get(buffer_key)
               end
@@ -76,35 +81,47 @@ module Gitlab
             end
 
             def write!(data)
+              raise ArgumentError, 'Could not write empty data' unless data.present?
+
               puts "#{self.class.name} - #{__callee__}: data.length: #{data.length.inspect} params[:chunk_index]: #{params[:chunk_index]}"
               Gitlab::Redis::Cache.with do |redis|
-                redis.set(buffer_key, data)
+                unless redis.set(buffer_key, data) == 'OK'
+                  raise WriteError, 'Failed to write'
+                end
+
                 redis.strlen(buffer_key)
               end
             end
 
             def append!(data)
+              raise ArgumentError, 'Could not write empty data' unless data.present?
+
               puts "#{self.class.name} - #{__callee__}: data.length: #{data.length.inspect} params[:chunk_index]: #{params[:chunk_index]}"
               Gitlab::Redis::Cache.with do |redis|
-                redis.append(buffer_key, data)
-                data.length
+                raise BufferKeyNotFoundError, 'Buffer key is not found' unless redis.exists(buffer_key)
+
+                original_size = size
+                new_size = redis.append(buffer_key, data)
+                appended_size = new_size - original_size
+
+                raise WriteError, 'Failed to append' unless appended_size == data.length
+
+                appended_size
               end
             end
 
             def truncate!(offset)
-              puts "#{self.class.name} - #{__callee__}: offset: #{offset.inspect} params[:chunk_index]: #{params[:chunk_index]}"
-              Gitlab::Redis::Cache.with do |redis|
-                return 0 unless redis.exists(buffer_key)
-
-                truncated_data = redis.getrange(buffer_key, 0, offset)
-                redis.set(buffer_key, truncated_data)
-              end
+              raise NotImplementedError
             end
 
             def delete!
               puts "#{self.class.name} - #{__callee__}: params[:chunk_index]: #{params[:chunk_index]}"
               Gitlab::Redis::Cache.with do |redis|
-                redis.del(buffer_key)
+                raise BufferKeyNotFoundError, 'Buffer key is not found' unless redis.exists(buffer_key)
+
+                unless redis.del(buffer_key) == 1
+                  raise WriteError, 'Failed to delete'
+                end
               end
             end
           end
diff --git a/lib/gitlab/ci/trace/chunked_file/chunked_io.rb b/lib/gitlab/ci/trace/chunked_file/chunked_io.rb
index 5a2c56a687b..f28955264c8 100644
--- a/lib/gitlab/ci/trace/chunked_file/chunked_io.rb
+++ b/lib/gitlab/ci/trace/chunked_file/chunked_io.rb
@@ -8,7 +8,7 @@ module Gitlab
     class Trace
       module ChunkedFile
         class ChunkedIO
-          extend ChunkedFile::Concerns::Opener
+          # extend ChunkedFile::Concerns::Opener
           include ChunkedFile::Concerns::Errors
           include ChunkedFile::Concerns::Hooks
           include ChunkedFile::Concerns::Callbacks
@@ -22,13 +22,21 @@ module Gitlab
 
           alias_method :pos, :tell
 
-          def initialize(job_id, size, mode = 'rb')
-            @size = size
+          def initialize(job_id, size = nil, mode = 'rb', &block)
+            raise NotImplementedError, "Mode 'w' is not supported" if mode.include?('w')
+
+            @size = size || calculate_size(job_id)
             @tell = 0
             @job_id = job_id
             @mode = mode
 
-            raise NotImplementedError, "Mode 'w' is not supported" if mode.include?('w')
+            if block_given?
+              begin
+                yield self
+              ensure
+                self.close
+              end
+            end
           end
 
           def close
@@ -128,7 +136,7 @@ module Gitlab
           end
 
           def present?
-            chunk_store.chunks_count(job_id) > 0
+            chunks_count > 0
           end
 
           def delete
@@ -177,19 +185,21 @@ module Gitlab
           end
 
           def write_chunk(data)
+            written_size = 0
+
             chunk_store.open(job_id, chunk_index, params_for_store) do |store|
               with_callbacks(:write_chunk, store) do
-                written_size = if buffer_size == data.length
+                written_size = if buffer_size == data.length || store.size == 0
                                  store.write!(data)
                                else
                                  store.append!(data)
                                end
 
                 raise WriteError, 'Written size mismatch' unless data.length == written_size
-
-                written_size
               end
             end
+
+            written_size
           end
 
           def truncate_chunk(offset)
@@ -228,7 +238,7 @@ module Gitlab
           end
 
           def chunks_count
-            (size / buffer_size)
+            (size / buffer_size.to_f).ceil
           end
 
           def first_chunk?
@@ -246,6 +256,10 @@ module Gitlab
           def buffer_size
             raise NotImplementedError
           end
+
+          def calculate_size(job_id)
+            chunk_store.chunks_size(job_id)
+          end
         end
       end
     end
diff --git a/lib/gitlab/ci/trace/chunked_file/concerns/hooks.rb b/lib/gitlab/ci/trace/chunked_file/concerns/hooks.rb
deleted file mode 100644
index 290a3a15805..00000000000
--- a/lib/gitlab/ci/trace/chunked_file/concerns/hooks.rb
+++ /dev/null
@@ -1,63 +0,0 @@
-module Gitlab
-  module Ci
-    class Trace
-      module ChunkedFile
-        module Concerns
-          module Hooks
-            extend ActiveSupport::Concern
-
-            included do
-              class_attribute :_before_methods, :_after_methods,
-                :instance_writer => false
-              self._before_methods = Hash.new []
-              self._after_methods = Hash.new []
-            end
-
-            class_methods do
-              def before_method(kind, callback)
-                self._before_methods = self._before_methods.
-                  merge kind => _before_methods[kind] + [callback]
-              end
-
-              def after_method(kind, callback)
-                self._after_methods = self._after_methods.
-                  merge kind => _after_methods[kind] + [callback]
-              end
-            end
-
-            def method_added(method_name)
-              return if self.class._before_methods.values.include?(method_name)
-              return if self.class._after_methods.values.include?(method_name)
-              return if hooked_methods.include?(method_name)
-
-              add_hooks_to(method_name)
-            end
-
-            private
-
-            def hooked_methods
-              @hooked_methods ||= []
-            end
-
-            def add_hooks_to(method_name)
-              hooked_methods << method_name
-
-              original_method = instance_method(method_name)
-
-              # re-define the method, but notice how we reference the original
-              # method definition
-              define_method(method_name) do |*args, &block|
-                self.class._before_methods[method_name].each { |hook| method(hook).call }
-
-                # now invoke the original method
-                original_method.bind(self).call(*args, &block).tap do
-                  self.class._after_methods[method_name].each { |hook| method(hook).call }
-                end
-              end
-            end
-          end
-        end
-      end
-    end
-  end
-end
diff --git a/lib/gitlab/ci/trace/chunked_file/concerns/permissions.rb b/lib/gitlab/ci/trace/chunked_file/concerns/permissions.rb
index f364237f07b..11d8fd0cdfc 100644
--- a/lib/gitlab/ci/trace/chunked_file/concerns/permissions.rb
+++ b/lib/gitlab/ci/trace/chunked_file/concerns/permissions.rb
@@ -6,28 +6,19 @@ module Gitlab
           module Permissions
             extend ActiveSupport::Concern
 
+            WRITABLE_MODE = %w[a]
+            READABLE_MODE = %w[r +]
+
             included do
               PermissionError = Class.new(StandardError)
 
               attr_reader :write_lock_uuid
-
-              # mode checks
-              before_method :read, :can_read!
-              before_method :readline, :can_read!
-              before_method :each_line, :can_read!
-              before_method :write, :can_write!
-              before_method :truncate, :can_write!
-
-              # write_lock
-              before_method :write, :check_lock!
-              before_method :truncate, :check_lock!
-              before_method :delete, :check_lock!
             end
 
             def initialize(job_id, size, mode = 'rb')
-              if /(w|a)/ =~ mode
+              if WRITABLE_MODE.any? { |m| mode.include?(m) }
                 @write_lock_uuid = Gitlab::ExclusiveLease
-                  .new(write_lock_key, timeout: 1.hour.to_i).try_obtain
+                  .new(write_lock_key(job_id), timeout: 1.hour.to_i).try_obtain
 
                 raise PermissionError, 'Already opened by another process' unless write_lock_uuid
               end
@@ -37,25 +28,63 @@ module Gitlab
 
             def close
               if write_lock_uuid
-                Gitlab::ExclusiveLease.cancel(write_lock_key, write_lock_uuid)
+                Gitlab::ExclusiveLease.cancel(write_lock_key(job_id), write_lock_uuid)
               end
 
               super
             end
 
-            def check_lock!
-              raise PermissionError, 'Could not modify the file without lock' unless write_lock_uuid
+            def read(*args)
+              can_read!
+
+              super
+            end
+
+            def readline(*args)
+              can_read!
+
+              super
+            end
+
+            def each_line(*args)
+              can_read!
+
+              super
             end
 
+            def write(*args)
+              can_write!
+
+              super
+            end
+
+            def truncate(*args)
+              can_write!
+
+              super
+            end
+
+            def delete(*args)
+              can_write!
+
+              super
+            end
+
+            private
+
             def can_read!
-              raise IOError, 'not opened for reading' unless /(r|+)/ =~ mode
+              unless READABLE_MODE.any? { |m| mode.include?(m) }
+                raise IOError, 'not opened for reading'
+              end
             end
 
             def can_write!
-              raise IOError, 'not opened for writing' unless /(w|a)/ =~ mode
+              unless WRITABLE_MODE.any? { |m| mode.include?(m) }
+                raise IOError, 'not opened for writing'
+              end
             end
 
-            def write_lock_key
+            def write_lock_key(job_id)
               "live_trace:operation:write:#{job_id}"
             end
           end
diff --git a/lib/gitlab/ci/trace/chunked_file/live_trace.rb b/lib/gitlab/ci/trace/chunked_file/live_trace.rb
index 6976686553f..fe2205144cb 100644
--- a/lib/gitlab/ci/trace/chunked_file/live_trace.rb
+++ b/lib/gitlab/ci/trace/chunked_file/live_trace.rb
@@ -12,10 +12,6 @@ module Gitlab
 
           after_callback :write_chunk, :stash_to_database
 
-          def initialize(job_id, mode)
-            super(job_id, calculate_size(job_id), mode)
-          end
-
           def stash_to_database(store)
             # Once data is filled into redis, move the data to database
             if store.filled?
diff --git a/spec/lib/gitlab/ci/trace/chunked_file/chunk_store/database_spec.rb b/spec/lib/gitlab/ci/trace/chunked_file/chunk_store/database_spec.rb
index 74fb81d7a53..c84398ca481 100644
--- a/spec/lib/gitlab/ci/trace/chunked_file/chunk_store/database_spec.rb
+++ b/spec/lib/gitlab/ci/trace/chunked_file/chunk_store/database_spec.rb
@@ -1,13 +1,13 @@
 require 'spec_helper'
 
 describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Database do
+  let(:job) { create(:ci_build) }
   let(:job_id) { job.id }
   let(:chunk_index) { 0 }
   let(:buffer_size) { 256 }
   let(:job_trace_chunk) { ::Ci::JobTraceChunk.new(job_id: job_id, chunk_index: chunk_index) }
   let(:params) { { buffer_size: buffer_size } }
-  let(:trace) { 'A' * buffer_size }
-  let(:job) { create(:ci_build) }
+  let(:data) { 'A' * buffer_size }
 
   describe '.open' do
     subject { described_class.open(job_id, chunk_index, params) }
@@ -35,7 +35,7 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Database do
 
     context 'when job_trace_chunk exists' do
       before do
-        described_class.new(job_trace_chunk, params).write!(trace)
+        described_class.new(job_trace_chunk, params).write!(data)
       end
 
       it { is_expected.to be_truthy }
@@ -51,17 +51,17 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Database do
 
     context 'when job_trace_chunk exists' do
       before do
-        described_class.new(job_trace_chunk, params).write!(trace)
+        described_class.new(job_trace_chunk, params).write!(data)
       end
 
       it { is_expected.to eq(1) }
 
       context 'when two chunks exists' do
         let(:job_trace_chunk_2) { ::Ci::JobTraceChunk.new(job_id: job_id, chunk_index: chunk_index + 1) }
-        let(:trace_2) { 'B' * buffer_size }
+        let(:data_2) { 'B' * buffer_size }
 
         before do
-          described_class.new(job_trace_chunk_2, params).write!(trace_2)
+          described_class.new(job_trace_chunk_2, params).write!(data_2)
         end
 
         it { is_expected.to eq(2) }
@@ -78,18 +78,18 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Database do
 
     context 'when job_trace_chunk exists' do
       before do
-        described_class.new(job_trace_chunk, params).write!(trace)
+        described_class.new(job_trace_chunk, params).write!(data)
       end
 
-      it { is_expected.to eq(trace.length) }
+      it { is_expected.to eq(data.length) }
 
       context 'when two chunks exists' do
         let(:job_trace_chunk_2) { ::Ci::JobTraceChunk.new(job_id: job_id, chunk_index: chunk_index + 1) }
-        let(:trace_2) { 'B' * buffer_size }
-        let(:chunks_size) { trace.length + trace_2.length }
+        let(:data_2) { 'B' * buffer_size }
+        let(:chunks_size) { data.length + data_2.length }
 
         before do
-          described_class.new(job_trace_chunk_2, params).write!(trace_2)
+          described_class.new(job_trace_chunk_2, params).write!(data_2)
         end
 
         it { is_expected.to eq(chunks_size) }
@@ -101,15 +101,48 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Database do
     end
   end
 
+  describe '.delete_all' do
+    subject { described_class.delete_all(job_id) }
+
+    context 'when job_trace_chunk exists' do
+      before do
+        described_class.new(job_trace_chunk, params).write!(data)
+      end
+
+      it 'deletes all' do
+        expect { subject }.to change { described_class.chunks_count(job_id) }.by(-1)
+      end
+
+      context 'when two chunks exists' do
+        let(:job_trace_chunk_2) { ::Ci::JobTraceChunk.new(job_id: job_id, chunk_index: chunk_index + 1) }
+        let(:data_2) { 'B' * buffer_size }
+
+        before do
+          described_class.new(job_trace_chunk_2, params).write!(data_2)
+        end
+
+        it 'deletes all' do
+          expect { subject }.to change { described_class.chunks_count(job_id) }.by(-2)
+        end
+      end
+    end
+
+    context 'when buffer_key does not exist' do
+      it 'deletes all' do
+        expect { subject }.not_to change { described_class.chunks_count(job_id) }
+      end
+    end
+  end
+
   describe '#get' do
     subject { described_class.new(job_trace_chunk, params).get }
 
     context 'when job_trace_chunk exists' do
       before do
-        described_class.new(job_trace_chunk, params).write!(trace)
+        described_class.new(job_trace_chunk, params).write!(data)
       end
 
-      it { is_expected.to eq(trace) }
+      it { is_expected.to eq(data) }
     end
 
     context 'when job_trace_chunk does not exist' do
@@ -122,10 +155,10 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Database do
 
     context 'when job_trace_chunk exists' do
       before do
-        described_class.new(job_trace_chunk, params).write!(trace)
+        described_class.new(job_trace_chunk, params).write!(data)
       end
 
-      it { is_expected.to eq(trace.length) }
+      it { is_expected.to eq(data.length) }
     end
 
     context 'when job_trace_chunk does not exist' do
@@ -134,45 +167,39 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Database do
   end
 
   describe '#write!' do
-    subject { described_class.new(job_trace_chunk, params).write!(trace) }
+    subject { described_class.new(job_trace_chunk, params).write!(data) }
 
     context 'when job_trace_chunk exists' do
       before do
-        described_class.new(job_trace_chunk, params).write!(trace)
+        described_class.new(job_trace_chunk, params).write!(data)
       end
 
-      it { expect { subject }.to raise_error('UPDATE is not supported') }
+      it { expect { subject }.to raise_error('UPDATE (Overwriting data) is not supported') }
     end
 
     context 'when job_trace_chunk does not exist' do
       let(:expected_data) { ::Ci::JobTraceChunk.find_by(job_id: job_id, chunk_index: chunk_index).data }
 
       it 'writes' do
-        is_expected.to eq(trace.length)
+        is_expected.to eq(data.length)
 
-        expect(expected_data).to eq(trace)
+        expect(expected_data).to eq(data)
       end
     end
 
     context 'when data is nil' do
-      let(:trace) { nil }
+      let(:data) { nil }
 
-      it { expect { subject }.to raise_error('Partial write is not supported') }
+      it { expect { subject }.to raise_error('Partial writing is not supported') }
     end
   end
 
-  describe '#truncate!' do
-    subject { described_class.new(job_trace_chunk, params).truncate!(0) }
-
-    it { expect { subject }.to raise_error(NotImplementedError) }
-  end
-
   describe '#delete!' do
     subject { described_class.new(job_trace_chunk, params).delete! }
 
     context 'when job_trace_chunk exists' do
       before do
-        described_class.new(job_trace_chunk, params).write!(trace)
+        described_class.new(job_trace_chunk, params).write!(data)
       end
 
       it 'deletes' do
@@ -187,14 +214,8 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Database do
     end
 
     context 'when job_trace_chunk does not exist' do
-      it 'deletes' do
-        expect(::Ci::JobTraceChunk.exists?(job_id: job_id, chunk_index: chunk_index))
-          .to be_falsy
-
-        subject
-
-        expect(::Ci::JobTraceChunk.exists?(job_id: job_id, chunk_index: chunk_index))
-          .to be_falsy
+      it 'raises an error' do
+        expect { subject }.to raise_error('Could not find deletable record')
       end
     end
   end
diff --git a/spec/lib/gitlab/ci/trace/chunked_file/chunk_store/redis_spec.rb b/spec/lib/gitlab/ci/trace/chunked_file/chunk_store/redis_spec.rb
index 83423ac2a33..f1fb64225c9 100644
--- a/spec/lib/gitlab/ci/trace/chunked_file/chunk_store/redis_spec.rb
+++ b/spec/lib/gitlab/ci/trace/chunked_file/chunk_store/redis_spec.rb
@@ -1,12 +1,13 @@
 require 'spec_helper'
 
 describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Redis, :clean_gitlab_redis_cache do
-  let(:job_id) { 1 }
+  let(:job) { create(:ci_build) }
+  let(:job_id) { job.id }
   let(:chunk_index) { 0 }
   let(:buffer_size) { 128.kilobytes }
   let(:buffer_key) { described_class.buffer_key(job_id, chunk_index) }
   let(:params) { { buffer_size: buffer_size } }
-  let(:trace) { 'Here is the trace' }
+  let(:data) { 'Here is the trace' }
 
   describe '.open' do
     subject { described_class.open(job_id, chunk_index, params) }
@@ -34,7 +35,7 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Redis, :clean_gitlab_redis_
 
     context 'when buffer_key exists' do
       before do
-        described_class.new(buffer_key, params).write!(trace)
+        described_class.new(buffer_key, params).write!(data)
       end
 
       it { is_expected.to be_truthy }
@@ -50,17 +51,17 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Redis, :clean_gitlab_redis_
 
     context 'when buffer_key exists' do
       before do
-        described_class.new(buffer_key, params).write!(trace)
+        described_class.new(buffer_key, params).write!(data)
       end
 
       it { is_expected.to eq(1) }
 
       context 'when two chunks exists' do
         let(:buffer_key_2) { described_class.buffer_key(job_id, chunk_index + 1) }
-        let(:trace_2) { 'Another trace' }
+        let(:data_2) { 'Another data' }
 
         before do
-          described_class.new(buffer_key_2, params).write!(trace_2)
+          described_class.new(buffer_key_2, params).write!(data_2)
         end
 
         it { is_expected.to eq(2) }
@@ -77,18 +78,18 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Redis, :clean_gitlab_redis_
 
     context 'when buffer_key exists' do
       before do
-        described_class.new(buffer_key, params).write!(trace)
+        described_class.new(buffer_key, params).write!(data)
       end
 
-      it { is_expected.to eq(trace.length) }
+      it { is_expected.to eq(data.length) }
 
       context 'when two chunks exists' do
         let(:buffer_key_2) { described_class.buffer_key(job_id, chunk_index + 1) }
-        let(:trace_2) { 'Another trace' }
-        let(:chunks_size) { trace.length + trace_2.length }
+        let(:data_2) { 'Another data' }
+        let(:chunks_size) { data.length + data_2.length }
 
         before do
-          described_class.new(buffer_key_2, params).write!(trace_2)
+          described_class.new(buffer_key_2, params).write!(data_2)
         end
 
         it { is_expected.to eq(chunks_size) }
@@ -100,6 +101,39 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Redis, :clean_gitlab_redis_
     end
   end
 
+  describe '.delete_all' do
+    subject { described_class.delete_all(job_id) }
+
+    context 'when buffer_key exists' do
+      before do
+        described_class.new(buffer_key, params).write!(data)
+      end
+
+      it 'deletes all' do
+        expect { subject }.to change { described_class.chunks_count(job_id) }.by(-1)
+      end
+
+      context 'when two chunks exists' do
+        let(:buffer_key_2) { described_class.buffer_key(job_id, chunk_index + 1) }
+        let(:data_2) { 'Another data' }
+
+        before do
+          described_class.new(buffer_key_2, params).write!(data_2)
+        end
+
+        it 'deletes all' do
+          expect { subject }.to change { described_class.chunks_count(job_id) }.by(-2)
+        end
+      end
+    end
+
+    context 'when buffer_key does not exist' do
+      it 'deletes all' do
+        expect { subject }.not_to change { described_class.chunks_count(job_id) }
+      end
+    end
+  end
+
   describe '.buffer_key' do
     subject { described_class.buffer_key(job_id, chunk_index) }
 
@@ -111,10 +145,10 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Redis, :clean_gitlab_redis_
 
     context 'when buffer_key exists' do
       before do
-        described_class.new(buffer_key, params).write!(trace)
+        described_class.new(buffer_key, params).write!(data)
       end
 
-      it { is_expected.to eq(trace) }
+      it { is_expected.to eq(data) }
     end
 
     context 'when buffer_key does not exist' do
@@ -127,10 +161,10 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Redis, :clean_gitlab_redis_
 
     context 'when buffer_key exists' do
       before do
-        described_class.new(buffer_key, params).write!(trace)
+        described_class.new(buffer_key, params).write!(data)
       end
 
-      it { is_expected.to eq(trace.length) }
+      it { is_expected.to eq(data.length) }
     end
 
     context 'when buffer_key does not exist' do
@@ -139,91 +173,72 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Redis, :clean_gitlab_redis_
   end
 
   describe '#write!' do
-    subject { described_class.new(buffer_key, params).write!(trace) }
+    subject { described_class.new(buffer_key, params).write!(data) }
 
     context 'when buffer_key exists' do
       before do
-        described_class.new(buffer_key, params).write!('Already data in the chunk')
+        described_class.new(buffer_key, params).write!('Already data in the data')
       end
 
       it 'overwrites' do
-        is_expected.to eq(trace.length)
+        is_expected.to eq(data.length)
 
         Gitlab::Redis::Cache.with do |redis|
-          expect(redis.get(buffer_key)).to eq(trace)
+          expect(redis.get(buffer_key)).to eq(data)
         end
       end
     end
 
     context 'when buffer_key does not exist' do
       it 'writes' do
-        is_expected.to eq(trace.length)
+        is_expected.to eq(data.length)
 
         Gitlab::Redis::Cache.with do |redis|
-          expect(redis.get(buffer_key)).to eq(trace)
+          expect(redis.get(buffer_key)).to eq(data)
         end
       end
     end
 
     context 'when data is nil' do
-      let(:trace) { nil }
+      let(:data) { nil }
 
       it 'clears value' do
-        is_expected.to eq(0)
+        expect { described_class.new(buffer_key, params).write!(data) }
+          .to raise_error('Could not write empty data')
       end
     end
   end
 
-  describe '#truncate!' do
-    subject { described_class.new(buffer_key, params).truncate!(offset) }
-
-    let(:offset) { 5 }
+  describe '#append!' do
+    subject { described_class.new(buffer_key, params).append!(data) }
 
     context 'when buffer_key exists' do
+      let(:written_chunk) { 'Already data in the data' }
+
       before do
-        described_class.new(buffer_key, params).write!(trace)
+        described_class.new(buffer_key, params).write!(written_chunk)
       end
 
-      it 'truncates' do
-        Gitlab::Redis::Cache.with do |redis|
-          expect(redis.get(buffer_key)).to eq(trace)
-        end
-
-        subject
+      it 'appends' do
+        is_expected.to eq(data.length)
 
         Gitlab::Redis::Cache.with do |redis|
-          expect(redis.get(buffer_key)).to eq(trace.slice(0..offset))
-        end
-      end
-
-      context 'when offset is larger than data size' do
-        let(:offset) { 100 }
-
-        it 'truncates' do
-          Gitlab::Redis::Cache.with do |redis|
-            expect(redis.get(buffer_key)).to eq(trace)
-          end
-
-          subject
-
-          Gitlab::Redis::Cache.with do |redis|
-            expect(redis.get(buffer_key)).to eq(trace.slice(0..offset))
-          end
+          expect(redis.get(buffer_key)).to eq(written_chunk + data)
         end
       end
     end
 
     context 'when buffer_key does not exist' do
-      it 'truncates' do
-        Gitlab::Redis::Cache.with do |redis|
-          expect(redis.get(buffer_key)).to be_nil
-        end
+      it 'raises an error' do
+        expect { subject }.to raise_error(described_class::BufferKeyNotFoundError)
+      end
+    end
 
-        subject
+    context 'when data is nil' do
+      let(:data) { nil }
 
-        Gitlab::Redis::Cache.with do |redis|
-          expect(redis.get(buffer_key)).to be_nil
-        end
+      it 'raises an error' do
+        expect { subject }.to raise_error('Could not write empty data')
       end
     end
   end
@@ -233,7 +248,7 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Redis, :clean_gitlab_redis_
 
     context 'when buffer_key exists' do
       before do
-        described_class.new(buffer_key, params).write!(trace)
+        described_class.new(buffer_key, params).write!(data)
       end
 
       it 'deletes' do
@@ -250,16 +265,8 @@ describe Gitlab::Ci::Trace::ChunkedFile::ChunkStore::Redis, :clean_gitlab_redis_
     end
 
     context 'when buffer_key does not exist' do
-      it 'deletes' do
-        Gitlab::Redis::Cache.with do |redis|
-          expect(redis.exists(buffer_key)).to be_falsy
-        end
-
-        subject
-
-        Gitlab::Redis::Cache.with do |redis|
-          expect(redis.exists(buffer_key)).to be_falsy
-        end
+      it 'raises an error' do
+        expect { subject }.to raise_error(described_class::BufferKeyNotFoundError)
       end
     end
   end
diff --git a/spec/lib/gitlab/ci/trace/chunked_file/chunked_io_spec.rb b/spec/lib/gitlab/ci/trace/chunked_file/chunked_io_spec.rb
index 048cad9f2e0..ffee27ca6e2 100644
--- a/spec/lib/gitlab/ci/trace/chunked_file/chunked_io_spec.rb
+++ b/spec/lib/gitlab/ci/trace/chunked_file/chunked_io_spec.rb
@@ -3,10 +3,9 @@ require 'spec_helper'
 describe Gitlab::Ci::Trace::ChunkedFile::ChunkedIO, :clean_gitlab_redis_cache do
   include ChunkedIOHelpers
 
-  let(:chunked_io) { described_class.new(job_id, size, mode) }
+  let(:chunked_io) { described_class.new(job_id, nil, mode) }
   let(:job) { create(:ci_build) }
   let(:job_id) { job.id }
-  let(:size) { sample_trace_size }
   let(:mode) { 'rb' }
 
   describe 'ChunkStore is Redis', :partial_support do
diff --git a/spec/support/chunked_io/chunked_io_helpers.rb b/spec/support/chunked_io/chunked_io_helpers.rb
index c12ad743c00..35b13bccdb4 100644
--- a/spec/support/chunked_io/chunked_io_helpers.rb
+++ b/spec/support/chunked_io/chunked_io_helpers.rb
@@ -1,6 +1,6 @@
 module ChunkedIOHelpers
   def fill_trace_to_chunks(data)
-    stream = described_class.new(job_id, data.length, 'wb')
+    stream = described_class.new(job_id, nil, 'a+b')
     stream.write(data)
     stream.close
   end
@@ -13,27 +13,23 @@ module ChunkedIOHelpers
     end
   end
 
-  def sample_trace_size
-    sample_trace_raw.length
-  end
-
-  def sample_trace_raw_for_live_trace
-    File.read(expand_fixture_path('trace/sample_trace'))
-  end
+  # def sample_trace_raw_for_live_trace
+  #   File.read(expand_fixture_path('trace/sample_trace'))
+  # end
 
-  def sample_trace_size_for_live_trace
-    sample_trace_raw_for_live_trace.length
-  end
+  # def sample_trace_size_for_live_trace
+  #   sample_trace_raw_for_live_trace.length
+  # end
 
-  def fill_trace_to_chunks_for_live_trace(data)
-    stream = described_class.new(job_id, 'wb')
-    stream.write(data)
-    stream.close
-  end
+  # def fill_trace_to_chunks_for_live_trace(data)
+  #   stream = described_class.new(job_id, 'a+b')
+  #   stream.write(data)
+  #   stream.close
+  # end
 
-  def stub_chunk_store_get_failed
-    allow_any_instance_of(chunk_store).to receive(:get).and_return(nil)
-  end
+  # def stub_chunk_store_get_failed
+  #   allow_any_instance_of(chunk_store).to receive(:get).and_return(nil)
+  # end
 
   def set_smaller_buffer_size_than(file_size)
     blocks = (file_size / 128)
diff --git a/spec/support/shared_examples/lib/gitlab/ci/trace/chunked_file/chunked_io_shared_examples.rb b/spec/support/shared_examples/lib/gitlab/ci/trace/chunked_file/chunked_io_shared_examples.rb
index 8bb3a6d8ff9..98199995182 100644
--- a/spec/support/shared_examples/lib/gitlab/ci/trace/chunked_file/chunked_io_shared_examples.rb
+++ b/spec/support/shared_examples/lib/gitlab/ci/trace/chunked_file/chunked_io_shared_examples.rb
@@ -8,53 +8,112 @@ shared_examples "ChunkedIO shared tests" do
       let(:mode) { 'rb' }
 
       it 'raises no exception' do
-        described_class.new(job_id, size, mode)
-
-        expect { described_class.new(job_id, size, mode) }.not_to raise_error
+        expect { described_class.new(job_id, nil, mode) }.not_to raise_error
+        expect { described_class.new(job_id, nil, mode) }.not_to raise_error
       end
     end
 
-    context 'when mode is write' do
+    context 'when mode is append' do
       let(:mode) { 'a+b' }
 
       it 'raises an exception' do
-        described_class.new(job_id, size, mode)
-
-        expect { described_class.new(job_id, size, mode) }.to raise_error('Already opened by another process')
+        expect { described_class.new(job_id, nil, mode) }.not_to raise_error
+        expect { described_class.new(job_id, nil, mode) }.to raise_error('Already opened by another process')
       end
 
       context 'when closed after open' do
         it 'does not raise an exception' do
-          described_class.new(job_id, size, mode).close
-
-          expect { described_class.new(job_id, size, mode) }.not_to raise_error
+          expect { described_class.new(job_id, nil, mode).close }.not_to raise_error
+          expect { described_class.new(job_id, nil, mode) }.not_to raise_error
         end
       end
     end
+
+    context 'when mode is write' do
+      let(:mode) { 'wb' }
+
+      it 'raises no exception' do
+        expect { described_class.new(job_id, nil, mode) }.to raise_error("Mode 'w' is not supported")
+      end
+    end
+  end
+
+  describe 'Permissions', :partial_support do
+    before do
+      fill_trace_to_chunks(sample_trace_raw)
+    end
+
+    context "when mode is 'a+b'" do
+      let(:mode) { 'a+b' }
+
+      it 'can write' do
+        expect { described_class.new(job_id, nil, mode).write('abc') }
+          .not_to raise_error
+      end
+
+      it 'can read' do
+        expect { described_class.new(job_id, nil, mode).read(10) }
+          .not_to raise_error
+      end
+    end
+
+    context "when mode is 'ab'" do
+      let(:mode) { 'ab' }
+
+      it 'can write' do
+        expect { described_class.new(job_id, nil, mode).write('abc') }
+          .not_to raise_error
+      end
+
+      it 'can not read' do
+        expect { described_class.new(job_id, nil, mode).read(10) }
+          .to raise_error('not opened for reading')
+      end
+    end
+
+    context "when mode is 'rb'" do
+      let(:mode) { 'rb' }
+
+      it 'can not write' do
+        expect { described_class.new(job_id, nil, mode).write('abc') }
+          .to raise_error('not opened for writing')
+      end
+
+      it 'can read' do
+        expect { described_class.new(job_id, nil, mode).read(10) }
+          .not_to raise_error
+      end
+    end
   end
 
   describe '#seek' do
     subject { chunked_io.seek(pos, where) }
 
+    before do
+      set_smaller_buffer_size_than(sample_trace_raw.length)
+      fill_trace_to_chunks(sample_trace_raw)
+    end
+
     context 'when moves pos to end of the file' do
       let(:pos) { 0 }
       let(:where) { IO::SEEK_END }
 
-      it { is_expected.to eq(size) }
+      it { is_expected.to eq(sample_trace_raw.length) }
     end
 
     context 'when moves pos to middle of the file' do
-      let(:pos) { size / 2 }
+      let(:pos) { sample_trace_raw.length / 2 }
       let(:where) { IO::SEEK_SET }
 
-      it { is_expected.to eq(size / 2) }
+      it { is_expected.to eq(pos) }
     end
 
     context 'when moves pos around' do
       it 'matches the result' do
         expect(chunked_io.seek(0)).to eq(0)
         expect(chunked_io.seek(100, IO::SEEK_CUR)).to eq(100)
-        expect { chunked_io.seek(size + 1, IO::SEEK_CUR) }.to raise_error('new position is outside of file')
+        expect { chunked_io.seek(sample_trace_raw.length + 1, IO::SEEK_CUR) }
+          .to raise_error('new position is outside of file')
       end
     end
   end
@@ -62,9 +121,14 @@ shared_examples "ChunkedIO shared tests" do
   describe '#eof?' do
     subject { chunked_io.eof? }
 
+    before do
+      set_smaller_buffer_size_than(sample_trace_raw.length)
+      fill_trace_to_chunks(sample_trace_raw)
+    end
+
     context 'when current pos is at end of the file' do
       before do
-        chunked_io.seek(size, IO::SEEK_SET)
+        chunked_io.seek(sample_trace_raw.length, IO::SEEK_SET)
       end
 
       it { is_expected.to be_truthy }
@@ -84,39 +148,39 @@ shared_examples "ChunkedIO shared tests" do
 
     context 'when buffer size is smaller than file size' do
       before do
-        set_smaller_buffer_size_than(size)
+        set_smaller_buffer_size_than(sample_trace_raw.length)
         fill_trace_to_chunks(sample_trace_raw)
       end
 
       it 'yields lines' do
-        expect { |b| described_class.new(job_id, size, 'rb').each_line(&b) }
+        expect { |b| described_class.new(job_id, nil, 'rb').each_line(&b) }
           .to yield_successive_args(*string_io.each_line.to_a)
       end
     end
 
     context 'when buffer size is larger than file size', :partial_support do
       before do
-        set_larger_buffer_size_than(size)
+        set_larger_buffer_size_than(sample_trace_raw.length)
         fill_trace_to_chunks(sample_trace_raw)
       end
 
       it 'calls get_chunk only once' do
         expect(chunk_store).to receive(:open).once.and_call_original
 
-        described_class.new(job_id, size, 'rb').each_line { |line| }
+        described_class.new(job_id, nil, 'rb').each_line { |line| }
       end
     end
   end
 
   describe '#read' do
-    subject { described_class.new(job_id, size, 'rb').read(length) }
+    subject { described_class.new(job_id, nil, 'rb').read(length) }
 
-    context 'when read whole size' do
+    context 'when read the whole size' do
       let(:length) { nil }
 
       context 'when buffer size is smaller than file size' do
         before do
-          set_smaller_buffer_size_than(size)
+          set_smaller_buffer_size_than(sample_trace_raw.length)
           fill_trace_to_chunks(sample_trace_raw)
         end
 
@@ -127,7 +191,7 @@ shared_examples "ChunkedIO shared tests" do
 
       context 'when buffer size is larger than file size', :partial_support do
         before do
-          set_larger_buffer_size_than(size)
+          set_larger_buffer_size_than(sample_trace_raw.length)
           fill_trace_to_chunks(sample_trace_raw)
         end
 
@@ -142,7 +206,7 @@ shared_examples "ChunkedIO shared tests" do
 
       context 'when buffer size is smaller than file size' do
         before do
-          set_smaller_buffer_size_than(size)
+          set_smaller_buffer_size_than(sample_trace_raw.length)
           fill_trace_to_chunks(sample_trace_raw)
         end
 
@@ -153,7 +217,7 @@ shared_examples "ChunkedIO shared tests" do
 
       context 'when buffer size is larger than file size', :partial_support do
         before do
-          set_larger_buffer_size_than(size)
+          set_larger_buffer_size_than(sample_trace_raw.length)
           fill_trace_to_chunks(sample_trace_raw)
         end
 
@@ -164,11 +228,11 @@ shared_examples "ChunkedIO shared tests" do
     end
 
     context 'when tries to read oversize' do
-      let(:length) { size + 1000 }
+      let(:length) { sample_trace_raw.length + 1000 }
 
       context 'when buffer size is smaller than file size' do
         before do
-          set_smaller_buffer_size_than(size)
+          set_smaller_buffer_size_than(sample_trace_raw.length)
           fill_trace_to_chunks(sample_trace_raw)
         end
 
@@ -179,7 +243,7 @@ shared_examples "ChunkedIO shared tests" do
 
       context 'when buffer size is larger than file size', :partial_support do
         before do
-          set_larger_buffer_size_than(size)
+          set_larger_buffer_size_than(sample_trace_raw.length)
           fill_trace_to_chunks(sample_trace_raw)
         end
 
@@ -194,7 +258,7 @@ shared_examples "ChunkedIO shared tests" do
 
       context 'when buffer size is smaller than file size' do
         before do
-          set_smaller_buffer_size_than(size)
+          set_smaller_buffer_size_than(sample_trace_raw.length)
           fill_trace_to_chunks(sample_trace_raw)
         end
 
@@ -205,7 +269,7 @@ shared_examples "ChunkedIO shared tests" do
 
       context 'when buffer size is larger than file size', :partial_support do
         before do
-          set_larger_buffer_size_than(size)
+          set_larger_buffer_size_than(sample_trace_raw.length)
           fill_trace_to_chunks(sample_trace_raw)
         end
 
@@ -214,21 +278,6 @@ shared_examples "ChunkedIO shared tests" do
         end
       end
     end
-
-    context 'when chunk store failed to get chunk' do
-      let(:length) { nil }
-
-      before do
-        set_smaller_buffer_size_than(size)
-        fill_trace_to_chunks(sample_trace_raw)
-
-        stub_chunk_store_get_failed
-      end
-
-      it 'reads a trace' do
-        expect { subject }.to raise_error(described_class::FailedToGetChunkError)
-      end
-    end
   end
 
   describe '#readline' do
@@ -244,23 +293,9 @@ shared_examples "ChunkedIO shared tests" do
       end
     end
 
-    context 'when chunk store failed to get chunk' do
-      let(:length) { nil }
-
-      before do
-        set_smaller_buffer_size_than(size)
-        fill_trace_to_chunks(sample_trace_raw)
-        stub_chunk_store_get_failed
-      end
-
-      it 'reads a trace' do
-        expect { subject }.to raise_error(described_class::FailedToGetChunkError)
-      end
-    end
-
     context 'when buffer size is smaller than file size' do
       before do
-        set_smaller_buffer_size_than(size)
+        set_smaller_buffer_size_than(sample_trace_raw.length)
         fill_trace_to_chunks(sample_trace_raw)
       end
 
@@ -269,7 +304,7 @@ shared_examples "ChunkedIO shared tests" do
 
     context 'when buffer size is larger than file size', :partial_support do
       before do
-        set_larger_buffer_size_than(size)
+        set_larger_buffer_size_than(sample_trace_raw.length)
         fill_trace_to_chunks(sample_trace_raw)
       end
 
@@ -278,11 +313,11 @@ shared_examples "ChunkedIO shared tests" do
 
     context 'when pos is at middle of the file' do
       before do
-        set_smaller_buffer_size_than(size)
+        set_smaller_buffer_size_than(sample_trace_raw.length)
         fill_trace_to_chunks(sample_trace_raw)
 
-        chunked_io.seek(size / 2)
-        string_io.seek(size / 2)
+        chunked_io.seek(chunked_io.size / 2)
+        string_io.seek(string_io.size / 2)
       end
 
       it 'reads from pos' do
@@ -296,171 +331,91 @@ shared_examples "ChunkedIO shared tests" do
 
     let(:data) { sample_trace_raw }
 
-    context 'when write mode' do
-      let(:mode) { 'wb' }
-
-      context 'when buffer size is smaller than file size' do
-        before do
-          set_smaller_buffer_size_than(size)
-        end
-
-        it 'writes a trace' do
-          is_expected.to eq(data.length)
+    context 'when append mode', :partial_support do
+      let(:mode) { 'a+b' }
 
-          described_class.open(job_id, size, 'rb') do |stream|
-            expect(stream.read).to eq(data)
-            expect(chunk_store.chunks_count(job_id)).to eq(stream.send(:chunks_count))
-            expect(chunk_store.chunks_size(job_id)).to eq(data.length)
+      context 'when data does not exist' do
+        context 'when buffer size is smaller than file size' do
+          before do
+            set_smaller_buffer_size_than(sample_trace_raw.length)
           end
-        end
-      end
-
-      context 'when buffer size is larger than file size', :partial_support do
-        before do
-          set_larger_buffer_size_than(size)
-        end
 
-        it 'writes a trace' do
-          is_expected.to eq(data.length)
+          it 'writes a trace' do
+            is_expected.to eq(data.length)
 
-          described_class.open(job_id, size, 'rb') do |stream|
-            expect(stream.read).to eq(data)
-            expect(chunk_store.chunks_count(job_id)).to eq(stream.send(:chunks_count))
-            expect(chunk_store.chunks_size(job_id)).to eq(data.length)
+            described_class.new(job_id, nil, 'rb') do |stream|
+              expect(stream.read).to eq(data)
+              expect(chunk_store.chunks_count(job_id)).to eq(stream.send(:chunks_count))
+              expect(chunk_store.chunks_size(job_id)).to eq(data.length)
+            end
           end
         end
-      end
 
-      context 'when data is nil' do
-        let(:data) { nil }
-
-        it 'writes a trace' do
-          expect { subject } .to raise_error('Could not write empty data')
-        end
-      end
-    end
-
-    context 'when append mode', :partial_support do
-      let(:original_data) { 'original data' }
-      let(:total_size) { original_data.length + data.length }
-
-      context 'when buffer size is smaller than file size' do
-        before do
-          set_smaller_buffer_size_than(size)
-          fill_trace_to_chunks(original_data)
-        end
-
-        it 'appends a trace' do
-          described_class.open(job_id, original_data.length, 'a+b') do |stream|
-            expect(stream.write(data)).to eq(data.length)
+        context 'when buffer size is larger than file size', :partial_support do
+          before do
+            set_larger_buffer_size_than(data.length)
           end
 
-          described_class.open(job_id, total_size, 'rb') do |stream|
-            expect(stream.read).to eq(original_data + data)
-            expect(chunk_store.chunks_count(job_id)).to eq(stream.send(:chunks_count))
-            expect(chunk_store.chunks_size(job_id)).to eq(total_size)
-          end
-        end
-      end
+          it 'writes a trace' do
+            is_expected.to eq(data.length)
 
-      context 'when buffer size is larger than file size' do
-        before do
-          set_larger_buffer_size_than(size)
-          fill_trace_to_chunks(original_data)
+            described_class.new(job_id, nil, 'rb') do |stream|
+              expect(stream.read).to eq(data)
+              expect(chunk_store.chunks_count(job_id)).to eq(stream.send(:chunks_count))
+              expect(chunk_store.chunks_size(job_id)).to eq(data.length)
+            end
+          end
         end
 
-        it 'appends a trace' do
-          described_class.open(job_id, original_data.length, 'a+b') do |stream|
-            expect(stream.write(data)).to eq(data.length)
-          end
+        context 'when data is nil' do
+          let(:data) { nil }
 
-          described_class.open(job_id, total_size, 'rb') do |stream|
-            expect(stream.read).to eq(original_data + data)
-            expect(chunk_store.chunks_count(job_id)).to eq(stream.send(:chunks_count))
-            expect(chunk_store.chunks_size(job_id)).to eq(total_size)
+          it 'writes a trace' do
+            expect { subject } .to raise_error('Could not write empty data')
           end
         end
       end
-    end
-  end
-
-  describe '#truncate' do
-    context 'when data exists' do
-      context 'when buffer size is smaller than file size' do
-        before do
-          set_smaller_buffer_size_than(size)
-          fill_trace_to_chunks(sample_trace_raw)
-        end
 
-        it 'truncates a trace' do
-          described_class.open(job_id, size, 'rb') do |stream|
-            expect(stream.read).to eq(sample_trace_raw)
-          end
+      context 'when data already exists' do
+        let(:exist_data) { 'exist data' }
+        let(:total_size) { exist_data.length + data.length }
 
-          described_class.open(job_id, size, 'wb') do |stream|
-            stream.truncate(0)
+        context 'when buffer size is smaller than file size' do
+          before do
+            set_smaller_buffer_size_than(data.length)
+            fill_trace_to_chunks(exist_data)
           end
 
-          described_class.open(job_id, 0, 'rb') do |stream|
-            expect(stream.read).to be_empty
-          end
-
-          expect(chunk_store.chunks_count(job_id)).to eq(0)
-          expect(chunk_store.chunks_size(job_id)).to eq(0)
-        end
-
-        context 'when offset is negative' do
-          it 'raises an error' do
-            described_class.open(job_id, size, 'wb') do |stream|
-              expect { stream.truncate(-1) }.to raise_error('Offset is out of bound')
+          it 'appends a trace' do
+            described_class.new(job_id, nil, 'a+b') do |stream|
+              expect(stream.write(data)).to eq(data.length)
             end
-          end
-        end
 
-        context 'when offset is larger than file size' do
-          it 'raises an error' do
-            described_class.open(job_id, size, 'wb') do |stream|
-              expect { stream.truncate(size + 1) }.to raise_error('Offset is out of bound')
+            described_class.new(job_id, nil, 'rb') do |stream|
+              expect(stream.read).to eq(exist_data + data)
+              expect(chunk_store.chunks_count(job_id)).to eq(stream.send(:chunks_count))
+              expect(chunk_store.chunks_size(job_id)).to eq(total_size)
             end
           end
         end
-      end
-
-      context 'when buffer size is larger than file size', :partial_support do
-        before do
-          set_larger_buffer_size_than(size)
-          fill_trace_to_chunks(sample_trace_raw)
-        end
 
-        it 'truncates a trace' do
-          described_class.open(job_id, size, 'rb') do |stream|
-            expect(stream.read).to eq(sample_trace_raw)
+        context 'when buffer size is larger than file size' do
+          before do
+            set_larger_buffer_size_than(data.length)
+            fill_trace_to_chunks(exist_data)
           end
 
-          described_class.open(job_id, size, 'wb') do |stream|
-            stream.truncate(0)
-          end
+          it 'appends a trace' do
+            described_class.new(job_id, nil, 'a+b') do |stream|
+              expect(stream.write(data)).to eq(data.length)
+            end
 
-          described_class.open(job_id, 0, 'rb') do |stream|
-            expect(stream.read).to be_empty
+            described_class.new(job_id, nil, 'rb') do |stream|
+              expect(stream.read).to eq(exist_data + data)
+              expect(chunk_store.chunks_count(job_id)).to eq(stream.send(:chunks_count))
+              expect(chunk_store.chunks_size(job_id)).to eq(total_size)
+            end
           end
-
-          expect(chunk_store.chunks_count(job_id)).to eq(0)
-          expect(chunk_store.chunks_size(job_id)).to eq(0)
-        end
-      end
-    end
-
-    context 'when data does not exist' do
-      before do
-        set_smaller_buffer_size_than(size)
-      end
-
-      it 'truncates a trace' do
-        described_class.open(job_id, size, 'wb') do |stream|
-          stream.truncate(0)
-          expect(stream.send(:tell)).to eq(0)
-          expect(stream.send(:size)).to eq(0)
         end
       end
     end