From f1a60e5c3e75688d2bc728771cc3c8dd8ffb20fe Mon Sep 17 00:00:00 2001
From: Dhruba Borthakur <dhruba@fb.com>
Date: Tue, 24 Sep 2013 22:23:19 -0700
Subject: [PATCH] The vector rep implementation was segfaulting because of
 incorrect initialization of vector.

Summary:
The constructor for Vector memtable has a parameter called 'count'
that specifies the capacity of the vector to be reserved at allocation
time. It was incorrectly used to initialize the size of the vector.

Test Plan: Enhanced db_test.

Reviewers: haobo, xjin, emayanke

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D13083
---
 db/db_test.cc                 | 2 +-
 include/rocksdb/memtablerep.h | 2 +-
 util/vectorrep.cc             | 4 ++--
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/db/db_test.cc b/db/db_test.cc
index 6802e4a34..1db529c44 100644
--- a/db/db_test.cc
+++ b/db/db_test.cc
@@ -335,7 +335,7 @@ class DBTest {
         options.memtable_factory.reset(new UnsortedRepFactory);
         break;
       case kVectorRep:
-        options.memtable_factory.reset(new VectorRepFactory);
+        options.memtable_factory.reset(new VectorRepFactory(100));
         break;
       case kUniversalCompaction:
         options.compaction_style = kCompactionStyleUniversal;
diff --git a/include/rocksdb/memtablerep.h b/include/rocksdb/memtablerep.h
index a2cb63f8f..209249837 100644
--- a/include/rocksdb/memtablerep.h
+++ b/include/rocksdb/memtablerep.h
@@ -152,7 +152,7 @@ class MemTableRepFactory {
 // Parameters:
 //   count: Passed to the constructor of the underlying std::vector of each
 //     VectorRep. On initialization, the underlying array will be at least count
-//     size.
+//     bytes reserved for usage.
 class VectorRepFactory : public MemTableRepFactory {
   const size_t count_;
 public:
diff --git a/util/vectorrep.cc b/util/vectorrep.cc
index 8770f60b9..744c9304c 100644
--- a/util/vectorrep.cc
+++ b/util/vectorrep.cc
@@ -123,10 +123,10 @@ size_t VectorRep::ApproximateMemoryUsage() {
 }
 
 VectorRep::VectorRep(const KeyComparator& compare, Arena* arena, size_t count)
-  : bucket_(new Bucket(count)),
+  : bucket_(new Bucket()),
     immutable_(false),
     sorted_(false),
-    compare_(compare) { }
+    compare_(compare) { bucket_.get()->reserve(count); }
 
 VectorRep::Iterator::Iterator(class VectorRep* vrep,
                    std::shared_ptr<std::vector<const char*>> bucket,