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avoid copying value twice during a get/1 (Howard Chu)

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This commit is contained in:
younes 2012-09-30 23:20:29 +02:00
parent e52c879b18
commit 1a435eb761
2 changed files with 8 additions and 19 deletions
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2
README.md
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@ -70,7 +70,7 @@ $ ./start.sh
####Note: ####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). 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. Performance ----------- For maximum speed, this library use only binaries for both keys and values.

25
c_src/emdb_drv.c
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@ -65,7 +65,6 @@ static struct emdb_map_t * emdb_map = NULL;
/* emdb errors */ /* emdb errors */
#define EMDB_MALLOC_ERR "error_malloc" #define EMDB_MALLOC_ERR "error_malloc"
#define EMDB_MAKE_BINARY_ERR "error_make_binary"
#define EMDB_CREATE_ERR "error_create" #define EMDB_CREATE_ERR "error_create"
#define EMDB_MAPSIZE_ERR "error_mapsize" #define EMDB_MAPSIZE_ERR "error_mapsize"
#define EMDB_OPEN_ERR "error_open" #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[]) int argc, const ERL_NIF_TERM argv[])
{ {
ErlNifBinary key; ErlNifBinary key;
ErlNifBinary val; ErlNifBinary val = {0};
/* ERL_NIF_TERM term; */ ERL_NIF_TERM term;
MDB_val mkey; MDB_val mkey;
MDB_val mdata; MDB_val mdata;
@ -274,26 +273,16 @@ static ERL_NIF_TERM emdb_get_nif (ErlNifEnv * env,
return atom_none; return atom_none;
} }
if (! enif_alloc_binary(mdata.mv_size, & val)) val.size = mdata.mv_size;
FAIL_FAST(EMDB_MALLOC_ERR, err2); val.data = mdata.mv_data;
memcpy(val.data, mdata.mv_data, mdata.mv_size); term = enif_make_binary(env, &val);
mdb_txn_abort(txn); mdb_txn_abort(txn);
return enif_make_tuple(env, 2, return enif_make_tuple(env, 2,
atom_ok, atom_ok,
enif_make_binary(env, & val)); term);
/* val.size = mdata.mv_size; */
/* val.data = mdata.mv_data; */
/* mdb_txn_abort(txn); */
/* return enif_make_tuple(env, 2, */
/* atom_ok, */
/* term); */
err2: err2:
mdb_txn_abort(txn); mdb_txn_abort(txn);