MXS-2067: Replace SPINLOCK with pthread_mutex_t

Replaced the SPINLOCK implementation with pthread_mutex_t. The SPINLOCK
interface is still used and will be removed later on.

include/maxscale/spinlock.h

@@ -12,103 +12,16 @@
  */
 #pragma once
 
-/**
- * @file spinlock.h
- *
- * Spinlock implementation for MaxScale.
- *
- * Spinlocks are cheap locks that can be used to protect short code blocks, they are
- * generally wasteful as any blocked threads will spin, consuming CPU cycles, waiting
- * for the lock to be released. However they are useful in that they do not involve
- * system calls and are light weight when the expected wait time for a lock is low.
- */
-
 #include <maxscale/cdefs.h>
 #include <stdbool.h>
+#include <pthread.h>
 
 MXS_BEGIN_DECLS
 
-#define SPINLOCK_PROFILE 0
-
-/**
- * The spinlock structure.
- *
- * In normal builds the structure merely contains a lock value which
- * is 0 if the spinlock is not taken and greater than zero if it is held.
- *
- * In builds with the SPINLOCK_PROFILE option set this structure also holds
- * a number of profile related fields that count the number of spins, number
- * of waiting threads and the number of times the lock has been acquired.
- */
-typedef struct spinlock
-{
-    int lock;               /*< Is the lock held? */
-#if SPINLOCK_PROFILE
-    uint64_t spins;         /*< Number of spins on this lock */
-    uint64_t maxspins;      /*< Max no of spins to acquire lock */
-    uint64_t acquired;      /*< No. of times lock was acquired */
-    uint64_t waiting;       /*< No. of threads acquiring this lock */
-    uint64_t max_waiting;   /*< Max no of threads waiting for lock */
-    uint64_t contended;     /*< No. of times acquire was contended */
-    THREAD   owner;         /*< Last owner of this lock */
-#endif
-} SPINLOCK;
-
-#if SPINLOCK_PROFILE
-#define SPINLOCK_INIT {0, 0, 0, 0, 0, 0, 0, 0}
-#else
-#define SPINLOCK_INIT {0}
-#endif
-
-/**
- * Debugging macro for testing the state of a spinlock.
- *
- * @attention ONLY to be used in debugging context.
- */
-#define SPINLOCK_IS_LOCKED(l) ((l)->lock != 0 ? true : false)
-
-/**
- * Initialise a spinlock.
- *
- * @param lock The spinlock to initialise.
- */
-extern void spinlock_init(SPINLOCK* lock);
-
-/**
- * Acquire a spinlock.
- *
- * @param lock The spinlock to acquire
- */
-extern void spinlock_acquire(const SPINLOCK* lock);
-
-/**
- * Acquire a spinlock if it is not already locked.
- *
- * @param lock The spinlock to acquire
- * @return True if the spinlock was acquired, otherwise false
- */
-extern bool spinlock_acquire_nowait(const SPINLOCK* lock);
-
-/*
- * Release a spinlock.
- *
- * @param lock The spinlock to release
- */
-extern void spinlock_release(const SPINLOCK* lock);
-
-/**
- * Report statistics on a spinlock. This only has an effect if the
- * spinlock code has been compiled with the SPINLOCK_PROFILE option set.
- *
- * NB A callback function is used to return the data rather than
- * merely printing to a DCB in order to avoid a dependency on the DCB
- * form the spinlock code and also to facilitate other uses of the
- * statistics reporting.
- *
- * @param lock          The spinlock to report on
- * @param reporter      The callback function to pass the statistics to
- * @param hdl           A handle that is passed to the reporter function
- */
-extern void spinlock_stats(const SPINLOCK* lock, void (* reporter)(void*, char*, int), void* hdl);
+#define SPINLOCK pthread_mutex_t
+#define SPINLOCK_INIT PTHREAD_MUTEX_INITIALIZER
+#define spinlock_init(a) pthread_mutex_init(a, NULL)
+#define spinlock_acquire(a) pthread_mutex_lock((pthread_mutex_t*)a)
+#define spinlock_release(a) pthread_mutex_unlock((pthread_mutex_t*)a)
 
 MXS_END_DECLS