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, 8 insertions, 0 deletions

diff --git a/mysql-test/mysql-test-run.pl b/mysql-test/mysql-test-run.pl
index 88f175b636f..19b9b97e22d 100755
--- a/mysql-test/mysql-test-run.pl
+++ b/mysql-test/mysql-test-run.pl
@@ -185,6 +185,7 @@ my $opt_ps_protocol;
 my $opt_sp_protocol;
 my $opt_cursor_protocol;
 my $opt_view_protocol;
+my $opt_non_blocking_api;
 
 our $opt_debug;
 our $opt_debug_server;
@@ -964,6 +965,7 @@ sub command_line_setup {
              'sp-protocol'              => \$opt_sp_protocol,
              'view-protocol'            => \$opt_view_protocol,
              'cursor-protocol'          => \$opt_cursor_protocol,
+             'non-blocking-api'         => \$opt_non_blocking_api,
              'ssl|with-openssl'         => \$opt_ssl,
              'skip-ssl'                 => \$opt_skip_ssl,
              'compress'                 => \$opt_compress,
@@ -5468,6 +5470,11 @@ sub start_mysqltest ($) {
     mtr_add_arg($args, "--cursor-protocol");
   }
 
+  if ( $opt_non_blocking_api )
+  {
+    mtr_add_arg($args, "--non-blocking-api");
+  }
+
   if ( $opt_strace_client )
   {
     $exe=  $opt_strace_client || "strace";
@@ -5915,6 +5922,7 @@ Options to control what engine/variation to run
                         (implies --ps-protocol)
   view-protocol         Create a view to execute all non updating queries
   sp-protocol           Create a stored procedure to execute all queries
+  non-blocking-api      Use the non-blocking client API
   compress              Use the compressed protocol between client and server
   ssl                   Use ssl protocol between client and server
   skip-ssl              Dont start server with support for ssl connections