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.

1 files changed, 23 insertions, 0 deletions

diff --git a/mysql-test/t/mysql_client_test_nonblock.test b/mysql-test/t/mysql_client_test_nonblock.test
new file mode 100644
index 00000000000..f212fe6abda
--- /dev/null
+++ b/mysql-test/t/mysql_client_test_nonblock.test
@@ -0,0 +1,23 @@
+# This runs the mysql_client_test using the non-blocking API.
+
+# This test should work in embedded server after we fix mysqltest
+-- source include/not_embedded.inc
+
+SET @old_general_log= @@global.general_log;
+SET @old_slow_query_log= @@global.slow_query_log;
+
+# We run with different binaries for normal and --embedded-server
+#
+# If this test fails with "command "$MYSQL_CLIENT_TEST" failed",
+# you should either run mysql_client_test separartely against a running
+# server or run mysql-test-run --debug mysql_client_test and check
+# var/log/mysql_client_test.trace
+
+--exec echo "$MYSQL_CLIENT_TEST --non-blocking-api" > $MYSQLTEST_VARDIR/log/mysql_client_test.out.log 2>&1
+--exec $MYSQL_CLIENT_TEST --non-blocking-api --getopt-ll-test=25600M >> $MYSQLTEST_VARDIR/log/mysql_client_test.out.log 2>&1
+
+# End of 4.1 tests
+echo ok;
+
+SET @@global.general_log= @old_general_log;
+SET @@global.slow_query_log= @old_slow_query_log;