From 9fc23d0c56db27a7ba164f5244fce802fea9578d Mon Sep 17 00:00:00 2001
From: Evan Shaw <edsrzf@gmail.com>
Date: Sun, 6 Jul 2014 10:35:13 +1200
Subject: [PATCH] C API: support constructing write batch from serialized
 representation

---
 db/c.cc             |  7 +++++++
 db/c_test.c         | 18 ++++++++++++++++++
 include/rocksdb/c.h |  2 ++
 3 files changed, 27 insertions(+)

diff --git a/db/c.cc b/db/c.cc
index 219f65094..78b8bcd54 100644
--- a/db/c.cc
+++ b/db/c.cc
@@ -607,6 +607,13 @@ rocksdb_writebatch_t* rocksdb_writebatch_create() {
   return new rocksdb_writebatch_t;
 }
 
+rocksdb_writebatch_t* rocksdb_writebatch_create_from(const char* rep,
+                                                     size_t size) {
+  rocksdb_writebatch_t* b = new rocksdb_writebatch_t;
+  b->rep = WriteBatch(std::string(rep, size));
+  return b;
+}
+
 void rocksdb_writebatch_destroy(rocksdb_writebatch_t* b) {
   delete b;
 }
diff --git a/db/c_test.c b/db/c_test.c
index 5220cd8a3..3ab47541a 100644
--- a/db/c_test.c
+++ b/db/c_test.c
@@ -299,6 +299,24 @@ int main(int argc, char** argv) {
     rocksdb_writebatch_destroy(wb);
   }
 
+  StartPhase("writebatch_rep");
+  {
+    rocksdb_writebatch_t* wb1 = rocksdb_writebatch_create();
+    rocksdb_writebatch_put(wb1, "baz", 3, "d", 1);
+    rocksdb_writebatch_put(wb1, "quux", 4, "e", 1);
+    rocksdb_writebatch_delete(wb1, "quux", 4);
+    size_t repsize1 = 0;
+    const char* rep = rocksdb_writebatch_data(wb1, &repsize1);
+    rocksdb_writebatch_t* wb2 = rocksdb_writebatch_create_from(rep, repsize1);
+    CheckCondition(rocksdb_writebatch_count(wb1) ==
+                   rocksdb_writebatch_count(wb2));
+    size_t repsize2 = 0;
+    CheckCondition(
+        memcmp(rep, rocksdb_writebatch_data(wb2, &repsize2), repsize1) == 0);
+    rocksdb_writebatch_destroy(wb1);
+    rocksdb_writebatch_destroy(wb2);
+  }
+
   StartPhase("iter");
   {
     rocksdb_iterator_t* iter = rocksdb_create_iterator(db, roptions);
diff --git a/include/rocksdb/c.h b/include/rocksdb/c.h
index c7d9f7782..6420c0eab 100644
--- a/include/rocksdb/c.h
+++ b/include/rocksdb/c.h
@@ -205,6 +205,8 @@ extern void rocksdb_iter_get_error(const rocksdb_iterator_t*, char** errptr);
 /* Write batch */
 
 extern rocksdb_writebatch_t* rocksdb_writebatch_create();
+extern rocksdb_writebatch_t* rocksdb_writebatch_create_from(const char* rep,
+                                                            size_t size);
 extern void rocksdb_writebatch_destroy(rocksdb_writebatch_t*);
 extern void rocksdb_writebatch_clear(rocksdb_writebatch_t*);
 extern int rocksdb_writebatch_count(rocksdb_writebatch_t*);