From 1a435eb761521c6ac7b91e7c0ca7c03529af8d0b Mon Sep 17 00:00:00 2001
From: younes <younes@aleph.local>
Date: Sun, 30 Sep 2012 23:20:29 +0200
Subject: [PATCH] avoid copying value twice during a get/1 (Howard Chu)

---
 README.md        |  2 +-
 c_src/emdb_drv.c | 25 +++++++------------------
 2 files changed, 8 insertions(+), 19 deletions(-)

diff --git a/README.md b/README.md
index bc32969..71237ea 100644
--- a/README.md
+++ b/README.md
@@ -70,7 +70,7 @@ $ ./start.sh
   
 
 ####Note:
-The code below create a new database with **80GB** MapSize, **avoid fsync**
+The code below creates a new database with **80GB** MapSize, **avoid fsync**
 after each commit (for max speed) and use the experimental **MDB_FIXEDMAP**.

	{ok, Handle} = emdb:open("/tmp/emdb2", 85899345920, ?MDB_NOSYNC bor ?MDB_FIXEDMAP).
 
	
 
Performance
-----------

For maximum speed, this library use only binaries for both keys and values.
diff --git a/c_src/emdb_drv.c b/c_src/emdb_drv.c
index 04e8dcf..8acff0f 100644
--- a/c_src/emdb_drv.c
+++ b/c_src/emdb_drv.c
@@ -65,7 +65,6 @@ static struct emdb_map_t * emdb_map = NULL;
 
 /* emdb errors */
 #define EMDB_MALLOC_ERR              "error_malloc"
-#define EMDB_MAKE_BINARY_ERR         "error_make_binary"
 #define EMDB_CREATE_ERR              "error_create"
 #define EMDB_MAPSIZE_ERR             "error_mapsize"
 #define EMDB_OPEN_ERR                "error_open"
@@ -237,8 +236,8 @@ static ERL_NIF_TERM emdb_get_nif (ErlNifEnv * env,
                                   int argc, const ERL_NIF_TERM argv[])
 {
   ErlNifBinary key;
-  ErlNifBinary val;
-/*   ERL_NIF_TERM term; */
+  ErlNifBinary val = {0};
+  ERL_NIF_TERM term;
 
   MDB_val mkey;
   MDB_val mdata;
@@ -274,26 +273,16 @@ static ERL_NIF_TERM emdb_get_nif (ErlNifEnv * env,
       return atom_none;
     }
 
-  if (! enif_alloc_binary(mdata.mv_size, & val))
-      FAIL_FAST(EMDB_MALLOC_ERR, err2);
-
-  memcpy(val.data, mdata.mv_data, mdata.mv_size);
+  val.size = mdata.mv_size;
+  val.data = mdata.mv_data;
+  
+  term = enif_make_binary(env, &val);
 
   mdb_txn_abort(txn);
 
   return enif_make_tuple(env, 2,
                          atom_ok,
-                         enif_make_binary(env, & val));
-
-/*   val.size = mdata.mv_size; */
-/*   val.data = mdata.mv_data; */
-  
-/*   mdb_txn_abort(txn); */
-
-/*   return enif_make_tuple(env, 2, */
-/*                          atom_ok, */
-/*                          term); */
-
+                         term);
 
  err2:
   mdb_txn_abort(txn);