Don't reuse gRPC channels

It seems that bad things happen when two gRPC stubs share one gRPC
channel so let's stop doing that. The downside of this is that we
create more gRPC connections; one per stub.

1 files changed, 25 insertions, 39 deletions

diff --git a/lib/gitlab/gitaly_client.rb b/lib/gitlab/gitaly_client.rb
index c69676a1dac..72466700c05 100644
--- a/lib/gitlab/gitaly_client.rb
+++ b/lib/gitlab/gitaly_client.rb
@@ -4,56 +4,42 @@ module Gitlab
   module GitalyClient
     SERVER_VERSION_FILE = 'GITALY_SERVER_VERSION'.freeze
 
-    # This function is not thread-safe because it updates Hashes in instance variables.
-    def self.configure_channels
-      @addresses = {}
-      @channels = {}
-      Gitlab.config.repositories.storages.each do |name, params|
-        address = params['gitaly_address']
-        unless address.present?
-          raise "storage #{name.inspect} is missing a gitaly_address"
-        end
+    MUTEX = Mutex.new
+    private_constant :MUTEX
 
-        unless URI(address).scheme.in?(%w(tcp unix))
-          raise "Unsupported Gitaly address: #{address.inspect} does not use URL scheme 'tcp' or 'unix'"
+    def self.stub(name, storage)
+      MUTEX.synchronize do
+        @stubs ||= {}
+        @stubs[storage] ||= {}
+        @stubs[storage][name] ||= begin
+          klass = Gitaly.const_get(name.to_s.camelcase.to_sym).const_get(:Stub)
+          addr = address(storage)
+          addr = addr.sub(%r{^tcp://}, '') if URI(addr).scheme == 'tcp'
+          klass.new(addr, :this_channel_is_insecure)
         end
-
-        @addresses[name] = address
-        @channels[name] = new_channel(address)
       end
     end
 
-    def self.new_channel(address)
-      address = address.sub(%r{^tcp://}, '') if URI(address).scheme == 'tcp'
-      # NOTE: When Gitaly runs on a Unix socket, permissions are
-      # handled using the file system and no additional authentication is
-      # required (therefore the :this_channel_is_insecure flag)
-      # TODO: Add authentication support when Gitaly is running on a TCP socket.
-      GRPC::Core::Channel.new(address, {}, :this_channel_is_insecure)
+    def self.clear_stubs!
+      MUTEX.synchronize do
+        @stubs = nil
+      end
     end
 
-    def self.get_channel(storage)
-      if !Rails.env.production? && @channels.nil?
-        # In development mode the Rails auto-loader may reset the instance
-        # variables of this class. What we do here is not thread-safe. In normal
-        # circumstances (including production) these instance variables have
-        # been initialized from config/initializers.
-        configure_channels
-      end
+    def self.address(storage)
+      params = Gitlab.config.repositories.storages[storage]
+      raise "storage not found: #{storage.inspect}" if params.nil?
 
-      @channels[storage]
-    end
+      address = params['gitaly_address']
+      unless address.present?
+        raise "storage #{storage.inspect} is missing a gitaly_address"
+      end
 
-    def self.get_address(storage)
-      if !Rails.env.production? && @addresses.nil?
-        # In development mode the Rails auto-loader may reset the instance
-        # variables of this class. What we do here is not thread-safe. In normal
-        # circumstances (including development) these instance variables have
-        # been initialized from config/initializers.
-        configure_channels
+      unless URI(address).scheme.in?(%w(tcp unix))
+        raise "Unsupported Gitaly address: #{address.inspect} does not use URL scheme 'tcp' or 'unix'"
       end
 
-      @addresses[storage]
+      address
     end
 
     def self.enabled?