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, 4 insertions, 0 deletions

diff --git a/vio/viosocket.c b/vio/viosocket.c
index 6c361e4a462..e60fe9bb225 100644
--- a/vio/viosocket.c
+++ b/vio/viosocket.c
@@ -98,6 +98,10 @@ size_t vio_read_buff(Vio *vio, uchar* buf, size_t size)
 #undef VIO_UNBUFFERED_READ_MIN_SIZE
 }
 
+my_bool vio_buff_has_data(Vio *vio)
+{
+  return (vio->read_pos != vio->read_end);
+}
 
 size_t vio_write(Vio * vio, const uchar* buf, size_t size)
 {