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Expose WriteBatch::Append().

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WriteBatchInternal has a method for efficiently concatenating two
WriteBatches. This commit exposes the method to the public API.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=208724311
This commit is contained in:
costan 2018-08-14 15:23:53 -07:00 committed by Victor Costan
parent 6caf73ad9d
commit f7b0e1d901
3 changed files with 15 additions and 4 deletions
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4
db/write_batch.cc
View File

@ -112,6 +112,10 @@ void WriteBatch::Delete(const Slice& key) {
PutLengthPrefixedSlice(&rep_, key);
}
void WriteBatch::Append(const WriteBatch &source) {
WriteBatchInternal::Append(this, &source);
}
namespace {
class MemTableInserter : public WriteBatch::Handler {
public:

8
db/write_batch_test.cc
View File

@ -91,21 +91,21 @@ TEST(WriteBatchTest, Append) {
WriteBatch b1, b2;
WriteBatchInternal::SetSequence(&b1, 200);
WriteBatchInternal::SetSequence(&b2, 300);
WriteBatchInternal::Append(&b1, &b2);
b1.Append(b2);
ASSERT_EQ("",
PrintContents(&b1));
b2.Put("a", "va");
WriteBatchInternal::Append(&b1, &b2);
b1.Append(b2);
ASSERT_EQ("Put(a, va)@200",
PrintContents(&b1));
b2.Clear();
b2.Put("b", "vb");
WriteBatchInternal::Append(&b1, &b2);
b1.Append(b2);
ASSERT_EQ("Put(a, va)@200"
"Put(b, vb)@201",
PrintContents(&b1));
b2.Delete("foo");
WriteBatchInternal::Append(&b1, &b2);
b1.Append(b2);
ASSERT_EQ("Put(a, va)@200"
"Put(b, vb)@202"
"Put(b, vb)@201"

7
include/leveldb/write_batch.h
View File

@ -54,6 +54,13 @@ class LEVELDB_EXPORT WriteBatch {
// releases. It is intended for LevelDB usage metrics.
size_t ApproximateSize();
// Copies the operations in "source" to this batch.
//
// This runs in O(source size) time. However, the constant factor is better
// than calling Iterate() over the source batch with a Handler that replicates
// the operations into this batch.
void Append(const WriteBatch& source);
// Support for iterating over the contents of a batch.
class Handler {
public: