From 2ba866e0c558521f6ba735e8861182038afcfc73 Mon Sep 17 00:00:00 2001
From: Abhishek Kona <abhishekk@fb.com>
Date: Tue, 11 Dec 2012 12:24:55 -0800
Subject: [PATCH] GetSequence API in write batch.

Summary:
WriteBatch is now used by the GetUpdatesSinceAPI. This API is external
and will be used by the rocks server. Rocks Server and others will need
to know about the Sequence Number in the WriteBatch. This public method
will allow for that.

Test Plan: make all check.

Reviewers: dhruba

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D7293
---
 db/db_test.cc                              | 8 ++++----
 db/transaction_log_iterator_impl.cc        | 4 +++-
 db/transaction_log_iterator_impl.h         | 2 +-
 include/leveldb/transaction_log_iterator.h | 5 +++--
 4 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/db/db_test.cc b/db/db_test.cc
index 808fd7605..117853c1e 100644
--- a/db/db_test.cc
+++ b/db/db_test.cc
@@ -2284,8 +2284,8 @@ TEST(DBTest, TransactionLogIterator) {
     SequenceNumber lastSequence = 0;
     while (iter->Valid()) {
       WriteBatch batch;
-      iter->GetBatch(&batch);
-      SequenceNumber current = WriteBatchInternal::Sequence(&batch);
+      SequenceNumber current;
+      iter->GetBatch(&batch, &current);
       ASSERT_TRUE(current > lastSequence);
       ++i;
       lastSequence = current;
@@ -2310,8 +2310,8 @@ TEST(DBTest, TransactionLogIterator) {
     SequenceNumber lastSequence = 0;
     while (iter->Valid()) {
       WriteBatch batch;
-      iter->GetBatch(&batch);
-      SequenceNumber current = WriteBatchInternal::Sequence(&batch);
+      SequenceNumber current;
+      iter->GetBatch(&batch, &current);
       ASSERT_TRUE(current > lastSequence);
       lastSequence = current;
       ASSERT_TRUE(iter->status().ok());
diff --git a/db/transaction_log_iterator_impl.cc b/db/transaction_log_iterator_impl.cc
index e2781a574..c2ca14a36 100644
--- a/db/transaction_log_iterator_impl.cc
+++ b/db/transaction_log_iterator_impl.cc
@@ -51,9 +51,11 @@ Status TransactionLogIteratorImpl::OpenLogFile(const LogFile& logFile,
   }
 }
 
-void TransactionLogIteratorImpl::GetBatch(WriteBatch* batch)  {
+void TransactionLogIteratorImpl::GetBatch(WriteBatch* batch,
+                                          SequenceNumber* seq)  {
   assert(isValid_);  //  cannot call in a non valid state.
   WriteBatchInternal::SetContents(batch, currentRecord_);
+  *seq = WriteBatchInternal::Sequence(batch);
 }
 
 Status TransactionLogIteratorImpl::status() {
diff --git a/db/transaction_log_iterator_impl.h b/db/transaction_log_iterator_impl.h
index 38b344f63..880032100 100644
--- a/db/transaction_log_iterator_impl.h
+++ b/db/transaction_log_iterator_impl.h
@@ -43,7 +43,7 @@ class TransactionLogIteratorImpl : public TransactionLogIterator {
 
   virtual Status status();
 
-  virtual void GetBatch(WriteBatch* batch);
+  virtual void GetBatch(WriteBatch* batch, SequenceNumber* seq);
 
  private:
   const std::string& dbname_;
diff --git a/include/leveldb/transaction_log_iterator.h b/include/leveldb/transaction_log_iterator.h
index 8f46cac80..a4bb99aa7 100644
--- a/include/leveldb/transaction_log_iterator.h
+++ b/include/leveldb/transaction_log_iterator.h
@@ -26,8 +26,9 @@ class TransactionLogIterator {
   // Return the Error Status when the iterator is not Valid.
   virtual Status status() = 0;
 
-  // If valid return's the current write_batch.
-  virtual void GetBatch(WriteBatch* batch) = 0;
+  // If valid return's the current write_batch and the sequence number of the
+  // latest transaction contained in the batch.
+  virtual void GetBatch(WriteBatch* batch, SequenceNumber* seq) = 0;
 };
 } //  namespace leveldb