New functionality to allow a pathway for writes with minimal overhead.

[ntdavidson]

Hi,

I've added a new function to allow developers to bypass the not insignificant overheads of (for example) using mongo_batch_insert and have a more direct path to mongo_env_write_socket. This, if used, can make significant savings in overhead by avoiding redundant calls such as memcpy and various other checks.

update: added a new commit with a test for mongo_fast_with_write_concern() and updated the benchmark to provide a comparison between mongo_batch_insert() and mongo_fast_with_write_concern().

Results on my system as follows; I expect with properly tuned network settings the results should be improved further.

serialize_small_test 8,051,529.790660
serialize_medium_test 2,258,355.916893
serialize_large_test 45,062.095568

serialize_small_test_fast 80,645,161.290323
serialize_medium_test_fast 48,076,923.076923
serialize_large_test_fast 124,134.164205

batch_insert_small_test_fast 155,593.589544
batch_insert_medium_test_fast 39,410.109481
batch_insert_large_test_fast 10,624.237711

batch_insert_small_test 34,433.838822
batch_insert_medium_test 47,975.436576
batch_insert_large_test 8,638.025278

[ntdavidson]

make test
sh runtests.sh
./test_unix_socket
./test_examples
0 : 3
name : 2 John Coltrane: Impressions
price : 16 1099

    1 : 3    
            name : 2         Larry Young: Unity
            price : 16       1199

./test_gridfs
./test_cpp
./test_sizes
./test_bson_alloc
./test_oid
./test_count_delete
./test_resize
./test_fast
./test_auth
./test_env_posix
./test_connect
./test_bson_subobject
./test_bcon
./test_update
./test_write_concern
./test_endian_swap
./test_simple
./test_cursors
./test_bson
d : 1 3.140000
s : 2 hello
s_n : 2 goodbye
o : 3
a : 4
0 : 5 BSON_BINDATA

    u : 6    BSON_UNDEFINED
    oid : 7          010203040506070809101112
    b : 8    true
    date : 9         72623859790382856
    n : 10   BSON_NULL
    r : 11   BSON_REGEX: ^asdf
    c : 13   BSON_CODE: function(){}
    c_n : 13         BSON_CODE: function(){}
    symbol : 14      SYMBOL: symbol
    symbol_n : 14    SYMBOL: symbol
    cws : 15         BSON_CODE_W_SCOPE: function(){return i}
     SCOPE:         i : 16   123

    timestamp : 17   i: 1, t: 2
    l : 18   1234605616436508552

sizeof(time_t) is 8

./test_helpers
v : 16 1
key : 3
foo : 16 -1

    unique : 8       true
    ns : 2   test.bar
    name : 2         foo_-1
    sparse : 8       true

./test_errors
./test_commands
./test_functions
Test printf 0
Test fprintf 0
Test sprintf 0
./test_validate

[ntdavidson]

scons test
scons: Reading SConscript files ...
Compiling for amd64
Checking for C library json... (cached) no
scons: done reading SConscript files.
scons: Building targets ...
gcc -o test/fast_test.o -c -std=c99 -pedantic -Wall -ggdb -DMONGO_HAVE_STDINT -D_POSIX_SOURCE -D_DARWIN_C_SOURCE -O3 -DMONGO_DLL_BUILD -DTEST_SERVER="127.0.0.1" -DSEED_START_PORT=30000 -Isrc test/fast_test.c
gcc -o test_fast test/fast_test.o -L. libmongoc.a libbson.a
/mnt/mongo-c-driver/test_write_concern 2> /dev/null
/mnt/mongo-c-driver/test_commands 2> /dev/null
/mnt/mongo-c-driver/test_sizes 2> /dev/null
/mnt/mongo-c-driver/test_resize 2> /dev/null
/mnt/mongo-c-driver/test_endian_swap 2> /dev/null
/mnt/mongo-c-driver/test_bson_alloc 2> /dev/null
/mnt/mongo-c-driver/test_bson 2> /dev/null
d : 1 3.140000
s : 2 hello
s_n : 2 goodbye
o : 3
a : 4
0 : 5 BSON_BINDATA

    u : 6    BSON_UNDEFINED
    oid : 7          010203040506070809101112
    b : 8    true
    date : 9         72623859790382856
    n : 10   BSON_NULL
    r : 11   BSON_REGEX: ^asdf
    c : 13   BSON_CODE: function(){}
    c_n : 13         BSON_CODE: function(){}
    symbol : 14      SYMBOL: symbol
    symbol_n : 14    SYMBOL: symbol
    cws : 15         BSON_CODE_W_SCOPE: function(){return i}
     SCOPE:         i : 16   123

    timestamp : 17   i: 1, t: 2
    l : 18   1234605616436508552

sizeof(time_t) is 8

/mnt/mongo-c-driver/test_bson_subobject 2> /dev/null
/mnt/mongo-c-driver/test_simple 2> /dev/null
/mnt/mongo-c-driver/test_update 2> /dev/null
/mnt/mongo-c-driver/test_errors 2> /dev/null
/mnt/mongo-c-driver/test_count_delete 2> /dev/null
/mnt/mongo-c-driver/test_auth 2> /dev/null
/mnt/mongo-c-driver/test_gridfs 2> /dev/null
/mnt/mongo-c-driver/test_validate 2> /dev/null
/mnt/mongo-c-driver/test_examples 2> /dev/null
0 : 3
name : 2 John Coltrane: Impressions
price : 16 1099

    1 : 3    
            name : 2         Larry Young: Unity
            price : 16       1199

/mnt/mongo-c-driver/test_helpers 2> /dev/null
v : 16 1
key : 3
foo : 16 -1

    unique : 8       true
    ns : 2   test.bar
    name : 2         foo_-1
    sparse : 8       true

/mnt/mongo-c-driver/test_oid 2> /dev/null
/mnt/mongo-c-driver/test_functions 2> /dev/null
Test printf 0
Test fprintf 0
Test sprintf 0
/mnt/mongo-c-driver/test_cursors 2> /dev/null
/mnt/mongo-c-driver/test_fast 2> /dev/null
/mnt/mongo-c-driver/test_bcon 2> /dev/null
/mnt/mongo-c-driver/test_env_posix 2> /dev/null
/mnt/mongo-c-driver/test_unix_socket 2> /dev/null
/mnt/mongo-c-driver/test_cpp 2> /dev/null
scons: done building targets.