MWL#192: Non-blocking client API for libmysqlclient.

All client functions that can block on I/O have alternate _start() and
_cont() versions that do not block but return control back to the
application, which can then issue I/O wait in its own fashion and later
call back into the library to continue the operation.

Works behind the scenes by spawning a co-routine/fiber to run the
blocking operation and suspend it while waiting for I/O. This
co-routine/fiber use is invisible to applications.

For i368/x86_64 on GCC, uses very fast assembler co-routine support. On
Windows uses native Win32 Fibers. Falls back to POSIX ucontext on other
platforms. Assembler routines for more platforms are relatively easy to
add by extending mysys/my_context.c, eg. similar to the Lua lcoco
library.

For testing, mysqltest and mysql_client_test are extended with the
option --non-blocking-api. This causes the programs to use the
non-blocking API for database access. mysql-test-run.pl has a similar
option --non-blocking-api that uses this, as well as additional
testcases.

An example program tests/async_queries.c is included that uses the new
non-blocking API with libevent to show how, in a single-threaded
program, to issue many queries in parallel against a database.


client/async_example.c:
  Fix const warning
  ******
  Fix bug with wrong timeout value for poll().
include/Makefile.am:
  Fix missing include for `make dist`
include/mysql.h:
  Add prototypes for all non-blocking API calls.
include/mysql.h.pp:
  Add prototypes for all non-blocking API calls.
mysys/my_context.c:
  Fix type warning for makecontext() function pointer argument.
sql-common/mysql_async.c:
  Fix crashes in the non-blocking API for functions that can take MYSQL argument
  that is NULL.
tests/Makefile.am:
  Add header file to `make dist`
tests/mysql_client_test.c:
  Replace blocking calls with wrappers around the non-blocking calls, used in
  mysql_client_test to test the new non-blocking API.
tests/nonblock-wrappers.h:
  Replace blocking calls with wrappers around the non-blocking calls, used in
  mysql_client_test to test the new non-blocking API.

2 files changed, 5 insertions, 3 deletions

diff --git a/libmysql/CMakeLists.txt b/libmysql/CMakeLists.txt
index 4ac0b9a01ee..fc781a6dffc 100755
--- a/libmysql/CMakeLists.txt
+++ b/libmysql/CMakeLists.txt
@@ -95,7 +95,8 @@ SET(CLIENT_SOURCES   ../mysys/array.c ../strings/bchange.c ../strings/bmove.c
                      ../strings/strtoll.c ../strings/strtoull.c ../strings/strxmov.c ../strings/strxnmov.c 
                      ../mysys/thr_mutex.c ../mysys/typelib.c ../vio/vio.c ../vio/viosocket.c 
                      ../vio/viossl.c ../vio/viosslfactories.c ../strings/xml.c ../mysys/mf_qsort.c
-                     ../mysys/my_getsystime.c ../mysys/my_sync.c ../sql-common/client_plugin.c ${LIB_SOURCES})
+                     ../mysys/my_getsystime.c ../mysys/my_sync.c ../sql-common/client_plugin.c
+		     ../sql-common/mysql_async.c ../mysys/my_context.c ${LIB_SOURCES})
 
 # Need to set USE_TLS for building the DLL, since __declspec(thread)
 # approach to thread local storage does not work properly in DLLs.
diff --git a/libmysql/Makefile.shared b/libmysql/Makefile.shared
index f9698f91a21..93bc527f915 100644
--- a/libmysql/Makefile.shared
+++ b/libmysql/Makefile.shared
@@ -71,9 +71,10 @@ mysysobjects1 =		my_init.lo my_static.lo my_malloc.lo my_realloc.lo \
                         mf_iocache2.lo my_seek.lo my_sleep.lo \
 			my_pread.lo mf_cache.lo md5.lo sha1.lo my_rnd.lo \
 			my_getopt.lo my_port.lo \
-                        my_rename.lo my_chsize.lo my_sync.lo my_getsystime.lo
+                        my_rename.lo my_chsize.lo my_sync.lo my_getsystime.lo \
+			my_context.lo
 sqlobjects =		net.lo
-sql_cmn_objects =	pack.lo client.lo my_time.lo client_plugin.lo
+sql_cmn_objects =	pack.lo client.lo my_time.lo client_plugin.lo mysql_async.lo
 
 # Not needed in the minimum library
 mysysobjects2 =		my_lib.lo mf_qsort.lo