1 files changed, 175 insertions, 0 deletions
diff --git a/leveldb/table/table.cc b/leveldb/table/table.cc
new file mode 100644
index 0000000..9820753
--- /dev/null
+++ b/leveldb/table/table.cc
@@ -0,0 +1,175 @@
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include "leveldb/table.h"
+
+#include "leveldb/cache.h"
+#include "leveldb/env.h"
+#include "table/block.h"
+#include "table/format.h"
+#include "table/two_level_iterator.h"
+#include "util/coding.h"
+
+namespace leveldb {
+
+struct Table::Rep {
+  ~Rep() {
+    delete index_block;
+  }
+
+  Options options;
+  Status status;
+  RandomAccessFile* file;
+  uint64_t cache_id;
+
+  BlockHandle metaindex_handle;  // Handle to metaindex_block: saved from footer
+  Block* index_block;
+};
+
+Status Table::Open(const Options& options,
+                   RandomAccessFile* file,
+                   uint64_t size,
+                   Table** table) {
+  *table = NULL;
+  if (size < Footer::kEncodedLength) {
+    return Status::InvalidArgument("file is too short to be an sstable");
+  }
+
+  char footer_space[Footer::kEncodedLength];
+  Slice footer_input;
+  Status s = file->Read(size - Footer::kEncodedLength, Footer::kEncodedLength,
+                        &footer_input, footer_space);
+  if (!s.ok()) return s;
+
+  Footer footer;
+  s = footer.DecodeFrom(&footer_input);
+  if (!s.ok()) return s;
+
+  // Read the index block
+  Block* index_block = NULL;
+  if (s.ok()) {
+    s = ReadBlock(file, ReadOptions(), footer.index_handle(), &index_block);
+  }
+
+  if (s.ok()) {
+    // We've successfully read the footer and the index block: we're
+    // ready to serve requests.
+    Rep* rep = new Table::Rep;
+    rep->options = options;
+    rep->file = file;
+    rep->metaindex_handle = footer.metaindex_handle();
+    rep->index_block = index_block;
+    rep->cache_id = (options.block_cache ? options.block_cache->NewId() : 0);
+    *table = new Table(rep);
+  } else {
+    if (index_block) delete index_block;
+  }
+
+  return s;
+}
+
+Table::~Table() {
+  delete rep_;
+}
+
+static void DeleteBlock(void* arg, void* ignored) {
+  delete reinterpret_cast<Block*>(arg);
+}
+
+static void DeleteCachedBlock(const Slice& key, void* value) {
+  Block* block = reinterpret_cast<Block*>(value);
+  delete block;
+}
+
+static void ReleaseBlock(void* arg, void* h) {
+  Cache* cache = reinterpret_cast<Cache*>(arg);
+  Cache::Handle* handle = reinterpret_cast<Cache::Handle*>(h);
+  cache->Release(handle);
+}
+
+// Convert an index iterator value (i.e., an encoded BlockHandle)
+// into an iterator over the contents of the corresponding block.
+Iterator* Table::BlockReader(void* arg,
+                             const ReadOptions& options,
+                             const Slice& index_value) {
+  Table* table = reinterpret_cast<Table*>(arg);
+  Cache* block_cache = table->rep_->options.block_cache;
+  Block* block = NULL;
+  Cache::Handle* cache_handle = NULL;
+
+  BlockHandle handle;
+  Slice input = index_value;
+  Status s = handle.DecodeFrom(&input);
+  // We intentionally allow extra stuff in index_value so that we
+  // can add more features in the future.
+
+  if (s.ok()) {
+    if (block_cache != NULL) {
+      char cache_key_buffer[16];
+      EncodeFixed64(cache_key_buffer, table->rep_->cache_id);
+      EncodeFixed64(cache_key_buffer+8, handle.offset());
+      Slice key(cache_key_buffer, sizeof(cache_key_buffer));
+      cache_handle = block_cache->Lookup(key);
+      if (cache_handle != NULL) {
+        block = reinterpret_cast<Block*>(block_cache->Value(cache_handle));
+      } else {
+        s = ReadBlock(table->rep_->file, options, handle, &block);
+        if (s.ok() && options.fill_cache) {
+          cache_handle = block_cache->Insert(
+              key, block, block->size(), &DeleteCachedBlock);
+        }
+      }
+    } else {
+      s = ReadBlock(table->rep_->file, options, handle, &block);
+    }
+  }
+
+  Iterator* iter;
+  if (block != NULL) {
+    iter = block->NewIterator(table->rep_->options.comparator);
+    if (cache_handle == NULL) {
+      iter->RegisterCleanup(&DeleteBlock, block, NULL);
+    } else {
+      iter->RegisterCleanup(&ReleaseBlock, block_cache, cache_handle);
+    }
+  } else {
+    iter = NewErrorIterator(s);
+  }
+  return iter;
+}
+
+Iterator* Table::NewIterator(const ReadOptions& options) const {
+  return NewTwoLevelIterator(
+      rep_->index_block->NewIterator(rep_->options.comparator),
+      &Table::BlockReader, const_cast<Table*>(this), options);
+}
+
+uint64_t Table::ApproximateOffsetOf(const Slice& key) const {
+  Iterator* index_iter =
+      rep_->index_block->NewIterator(rep_->options.comparator);
+  index_iter->Seek(key);
+  uint64_t result;
+  if (index_iter->Valid()) {
+    BlockHandle handle;
+    Slice input = index_iter->value();
+    Status s = handle.DecodeFrom(&input);
+    if (s.ok()) {
+      result = handle.offset();
+    } else {
+      // Strange: we can't decode the block handle in the index block.
+      // We'll just return the offset of the metaindex block, which is
+      // close to the whole file size for this case.
+      result = rep_->metaindex_handle.offset();
+    }
+  } else {
+    // key is past the last key in the file.  Approximate the offset
+    // by returning the offset of the metaindex block (which is
+    // right near the end of the file).
+    result = rep_->metaindex_handle.offset();
+  }
+  delete index_iter;
+  return result;
+}
+
+}