aboutsummaryrefslogtreecommitdiff
path: root/src/leveldb/table/table_builder.cc
diff options
context:
space:
mode:
Diffstat (limited to 'src/leveldb/table/table_builder.cc')
-rw-r--r--src/leveldb/table/table_builder.cc270
1 files changed, 270 insertions, 0 deletions
diff --git a/src/leveldb/table/table_builder.cc b/src/leveldb/table/table_builder.cc
new file mode 100644
index 0000000000..62002c84f2
--- /dev/null
+++ b/src/leveldb/table/table_builder.cc
@@ -0,0 +1,270 @@
+// 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_builder.h"
+
+#include <assert.h>
+#include "leveldb/comparator.h"
+#include "leveldb/env.h"
+#include "leveldb/filter_policy.h"
+#include "leveldb/options.h"
+#include "table/block_builder.h"
+#include "table/filter_block.h"
+#include "table/format.h"
+#include "util/coding.h"
+#include "util/crc32c.h"
+
+namespace leveldb {
+
+struct TableBuilder::Rep {
+ Options options;
+ Options index_block_options;
+ WritableFile* file;
+ uint64_t offset;
+ Status status;
+ BlockBuilder data_block;
+ BlockBuilder index_block;
+ std::string last_key;
+ int64_t num_entries;
+ bool closed; // Either Finish() or Abandon() has been called.
+ FilterBlockBuilder* filter_block;
+
+ // We do not emit the index entry for a block until we have seen the
+ // first key for the next data block. This allows us to use shorter
+ // keys in the index block. For example, consider a block boundary
+ // between the keys "the quick brown fox" and "the who". We can use
+ // "the r" as the key for the index block entry since it is >= all
+ // entries in the first block and < all entries in subsequent
+ // blocks.
+ //
+ // Invariant: r->pending_index_entry is true only if data_block is empty.
+ bool pending_index_entry;
+ BlockHandle pending_handle; // Handle to add to index block
+
+ std::string compressed_output;
+
+ Rep(const Options& opt, WritableFile* f)
+ : options(opt),
+ index_block_options(opt),
+ file(f),
+ offset(0),
+ data_block(&options),
+ index_block(&index_block_options),
+ num_entries(0),
+ closed(false),
+ filter_block(opt.filter_policy == NULL ? NULL
+ : new FilterBlockBuilder(opt.filter_policy)),
+ pending_index_entry(false) {
+ index_block_options.block_restart_interval = 1;
+ }
+};
+
+TableBuilder::TableBuilder(const Options& options, WritableFile* file)
+ : rep_(new Rep(options, file)) {
+ if (rep_->filter_block != NULL) {
+ rep_->filter_block->StartBlock(0);
+ }
+}
+
+TableBuilder::~TableBuilder() {
+ assert(rep_->closed); // Catch errors where caller forgot to call Finish()
+ delete rep_->filter_block;
+ delete rep_;
+}
+
+Status TableBuilder::ChangeOptions(const Options& options) {
+ // Note: if more fields are added to Options, update
+ // this function to catch changes that should not be allowed to
+ // change in the middle of building a Table.
+ if (options.comparator != rep_->options.comparator) {
+ return Status::InvalidArgument("changing comparator while building table");
+ }
+
+ // Note that any live BlockBuilders point to rep_->options and therefore
+ // will automatically pick up the updated options.
+ rep_->options = options;
+ rep_->index_block_options = options;
+ rep_->index_block_options.block_restart_interval = 1;
+ return Status::OK();
+}
+
+void TableBuilder::Add(const Slice& key, const Slice& value) {
+ Rep* r = rep_;
+ assert(!r->closed);
+ if (!ok()) return;
+ if (r->num_entries > 0) {
+ assert(r->options.comparator->Compare(key, Slice(r->last_key)) > 0);
+ }
+
+ if (r->pending_index_entry) {
+ assert(r->data_block.empty());
+ r->options.comparator->FindShortestSeparator(&r->last_key, key);
+ std::string handle_encoding;
+ r->pending_handle.EncodeTo(&handle_encoding);
+ r->index_block.Add(r->last_key, Slice(handle_encoding));
+ r->pending_index_entry = false;
+ }
+
+ if (r->filter_block != NULL) {
+ r->filter_block->AddKey(key);
+ }
+
+ r->last_key.assign(key.data(), key.size());
+ r->num_entries++;
+ r->data_block.Add(key, value);
+
+ const size_t estimated_block_size = r->data_block.CurrentSizeEstimate();
+ if (estimated_block_size >= r->options.block_size) {
+ Flush();
+ }
+}
+
+void TableBuilder::Flush() {
+ Rep* r = rep_;
+ assert(!r->closed);
+ if (!ok()) return;
+ if (r->data_block.empty()) return;
+ assert(!r->pending_index_entry);
+ WriteBlock(&r->data_block, &r->pending_handle);
+ if (ok()) {
+ r->pending_index_entry = true;
+ r->status = r->file->Flush();
+ }
+ if (r->filter_block != NULL) {
+ r->filter_block->StartBlock(r->offset);
+ }
+}
+
+void TableBuilder::WriteBlock(BlockBuilder* block, BlockHandle* handle) {
+ // File format contains a sequence of blocks where each block has:
+ // block_data: uint8[n]
+ // type: uint8
+ // crc: uint32
+ assert(ok());
+ Rep* r = rep_;
+ Slice raw = block->Finish();
+
+ Slice block_contents;
+ CompressionType type = r->options.compression;
+ // TODO(postrelease): Support more compression options: zlib?
+ switch (type) {
+ case kNoCompression:
+ block_contents = raw;
+ break;
+
+ case kSnappyCompression: {
+ std::string* compressed = &r->compressed_output;
+ if (port::Snappy_Compress(raw.data(), raw.size(), compressed) &&
+ compressed->size() < raw.size() - (raw.size() / 8u)) {
+ block_contents = *compressed;
+ } else {
+ // Snappy not supported, or compressed less than 12.5%, so just
+ // store uncompressed form
+ block_contents = raw;
+ type = kNoCompression;
+ }
+ break;
+ }
+ }
+ WriteRawBlock(block_contents, type, handle);
+ r->compressed_output.clear();
+ block->Reset();
+}
+
+void TableBuilder::WriteRawBlock(const Slice& block_contents,
+ CompressionType type,
+ BlockHandle* handle) {
+ Rep* r = rep_;
+ handle->set_offset(r->offset);
+ handle->set_size(block_contents.size());
+ r->status = r->file->Append(block_contents);
+ if (r->status.ok()) {
+ char trailer[kBlockTrailerSize];
+ trailer[0] = type;
+ uint32_t crc = crc32c::Value(block_contents.data(), block_contents.size());
+ crc = crc32c::Extend(crc, trailer, 1); // Extend crc to cover block type
+ EncodeFixed32(trailer+1, crc32c::Mask(crc));
+ r->status = r->file->Append(Slice(trailer, kBlockTrailerSize));
+ if (r->status.ok()) {
+ r->offset += block_contents.size() + kBlockTrailerSize;
+ }
+ }
+}
+
+Status TableBuilder::status() const {
+ return rep_->status;
+}
+
+Status TableBuilder::Finish() {
+ Rep* r = rep_;
+ Flush();
+ assert(!r->closed);
+ r->closed = true;
+
+ BlockHandle filter_block_handle, metaindex_block_handle, index_block_handle;
+
+ // Write filter block
+ if (ok() && r->filter_block != NULL) {
+ WriteRawBlock(r->filter_block->Finish(), kNoCompression,
+ &filter_block_handle);
+ }
+
+ // Write metaindex block
+ if (ok()) {
+ BlockBuilder meta_index_block(&r->options);
+ if (r->filter_block != NULL) {
+ // Add mapping from "filter.Name" to location of filter data
+ std::string key = "filter.";
+ key.append(r->options.filter_policy->Name());
+ std::string handle_encoding;
+ filter_block_handle.EncodeTo(&handle_encoding);
+ meta_index_block.Add(key, handle_encoding);
+ }
+
+ // TODO(postrelease): Add stats and other meta blocks
+ WriteBlock(&meta_index_block, &metaindex_block_handle);
+ }
+
+ // Write index block
+ if (ok()) {
+ if (r->pending_index_entry) {
+ r->options.comparator->FindShortSuccessor(&r->last_key);
+ std::string handle_encoding;
+ r->pending_handle.EncodeTo(&handle_encoding);
+ r->index_block.Add(r->last_key, Slice(handle_encoding));
+ r->pending_index_entry = false;
+ }
+ WriteBlock(&r->index_block, &index_block_handle);
+ }
+
+ // Write footer
+ if (ok()) {
+ Footer footer;
+ footer.set_metaindex_handle(metaindex_block_handle);
+ footer.set_index_handle(index_block_handle);
+ std::string footer_encoding;
+ footer.EncodeTo(&footer_encoding);
+ r->status = r->file->Append(footer_encoding);
+ if (r->status.ok()) {
+ r->offset += footer_encoding.size();
+ }
+ }
+ return r->status;
+}
+
+void TableBuilder::Abandon() {
+ Rep* r = rep_;
+ assert(!r->closed);
+ r->closed = true;
+}
+
+uint64_t TableBuilder::NumEntries() const {
+ return rep_->num_entries;
+}
+
+uint64_t TableBuilder::FileSize() const {
+ return rep_->offset;
+}
+
+} // namespace leveldb