WL#5363: Thread Pool Service Interface

In order to allow thread schedulers to be dynamically loaded,
it is necessary to make the following changes to the server:

- Two new service interfaces

- Modifications to InnoDB to inform the thread scheduler of state changes.

- Changes to the VIO subsystem for checking if data is available on a socket.

- Elimination of remains of the old thread pool implementation.

The two new service interfaces introduces are:

my_thread_scheduler
  A service interface to register a thread
  scheduler.

thd_wait
  A service interface to inform thread scheduler
  that the thread is about to start waiting.

In addition, the patch adds code that:

- Add a call to thd_wait for table locks in mysys
  thd_lock.c by introducing a set function that
  can be used to set a callback to be used when
  waiting on a lock and resuming from waiting.

- Calling the mysys set function from the server
  to set the callbacks correctly.

1 files changed, 2 insertions, 17 deletions

diff --git a/sql/sys_vars.cc b/sql/sys_vars.cc
index b5df2ae58c1..e743e994444 100644
--- a/sql/sys_vars.cc
+++ b/sql/sys_vars.cc
@@ -1658,19 +1658,13 @@ static Sys_var_ulong Sys_trans_prealloc_size(
 
 static const char *thread_handling_names[]=
 {
-  "one-thread-per-connection", "no-threads",
-#if HAVE_POOL_OF_THREADS == 1
-  "pool-of-threads",
-#endif
+  "one-thread-per-connection", "no-threads", "loaded-dynamically",
   0
 };
 static Sys_var_enum Sys_thread_handling(
        "thread_handling",
        "Define threads usage for handling queries, one of "
-       "one-thread-per-connection, no-threads"
-#if HAVE_POOL_OF_THREADS == 1
-       ", pool-of-threads"
-#endif
+       "one-thread-per-connection, no-threads, loaded-dynamically"
        , READ_ONLY GLOBAL_VAR(thread_handling), CMD_LINE(REQUIRED_ARG),
        thread_handling_names, DEFAULT(0));
 
@@ -1997,15 +1991,6 @@ static Sys_var_ulong Sys_thread_cache_size(
        GLOBAL_VAR(thread_cache_size), CMD_LINE(REQUIRED_ARG),
        VALID_RANGE(0, 16384), DEFAULT(0), BLOCK_SIZE(1));
 
-#if HAVE_POOL_OF_THREADS == 1
-static Sys_var_ulong Sys_thread_pool_size(
-       "thread_pool_size",
-       "How many threads we should create to handle query requests in "
-       "case of 'thread_handling=pool-of-threads'",
-       GLOBAL_VAR(thread_pool_size), CMD_LINE(REQUIRED_ARG),
-       VALID_RANGE(1, 16384), DEFAULT(20), BLOCK_SIZE(0));
-#endif
-
 //  Can't change the 'next' tx_isolation if we are already in a transaction
 static bool check_tx_isolation(sys_var *self, THD *thd, set_var *var)
 {