debug_sync is now a service, available to dynamically loaded plugins.

new make target - abi_update

libservices/HOWTO:
  remove references to Makefile.am
  small tweaks

7 files changed, 18 insertions, 366 deletions

diff --git a/sql/debug_sync.cc b/sql/debug_sync.cc
index a789763dd25..4097d7fe6e1 100644
--- a/sql/debug_sync.cc
+++ b/sql/debug_sync.cc
@@ -13,307 +13,7 @@
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
-/**
-  == Debug Sync Facility ==
-
-  The Debug Sync Facility allows placement of synchronization points in
-  the server code by using the DEBUG_SYNC macro:
-
-      open_tables(...)
-
-      DEBUG_SYNC(thd, "after_open_tables");
-
-      lock_tables(...)
-
-  When activated, a sync point can
-
-    - Emit a signal and/or
-    - Wait for a signal
-
-  Nomenclature:
-
-    - signal:             A value of a global variable that persists
-                          until overwritten by a new signal. The global
-                          variable can also be seen as a "signal post"
-                          or "flag mast". Then the signal is what is
-                          attached to the "signal post" or "flag mast".
-
-    - emit a signal:      Assign the value (the signal) to the global
-                          variable ("set a flag") and broadcast a
-                          global condition to wake those waiting for
-                          a signal.
-
-    - wait for a signal:  Loop over waiting for the global condition until
-                          the global value matches the wait-for signal.
-
-  By default, all sync points are inactive. They do nothing (except to
-  burn a couple of CPU cycles for checking if they are active).
-
-  A sync point becomes active when an action is requested for it.
-  To do so, put a line like this in the test case file:
-
-      SET DEBUG_SYNC= 'after_open_tables SIGNAL opened WAIT_FOR flushed';
-
-  This activates the sync point 'after_open_tables'. It requests it to
-  emit the signal 'opened' and wait for another thread to emit the signal
-  'flushed' when the thread's execution runs through the sync point.
-
-  For every sync point there can be one action per thread only. Every
-  thread can request multiple actions, but only one per sync point. In
-  other words, a thread can activate multiple sync points.
-
-  Here is an example how to activate and use the sync points:
-
-      --connection conn1
-      SET DEBUG_SYNC= 'after_open_tables SIGNAL opened WAIT_FOR flushed';
-      send INSERT INTO t1 VALUES(1);
-          --connection conn2
-          SET DEBUG_SYNC= 'now WAIT_FOR opened';
-          SET DEBUG_SYNC= 'after_abort_locks SIGNAL flushed';
-          FLUSH TABLE t1;
-
-  When conn1 runs through the INSERT statement, it hits the sync point
-  'after_open_tables'. It notices that it is active and executes its
-  action. It emits the signal 'opened' and waits for another thread to
-  emit the signal 'flushed'.
-
-  conn2 waits immediately at the special sync point 'now' for another
-  thread to emit the 'opened' signal.
-
-  A signal remains in effect until it is overwritten. If conn1 signals
-  'opened' before conn2 reaches 'now', conn2 will still find the 'opened'
-  signal. It does not wait in this case.
-
-  When conn2 reaches 'after_abort_locks', it signals 'flushed', which lets
-  conn1 awake.
-
-  Normally the activation of a sync point is cleared when it has been
-  executed. Sometimes it is necessary to keep the sync point active for
-  another execution. You can add an execute count to the action:
-
-      SET DEBUG_SYNC= 'name SIGNAL sig EXECUTE 3';
-
-  This sets the signal point's activation counter to 3. Each execution
-  decrements the counter. After the third execution the sync point
-  becomes inactive.
-
-  One of the primary goals of this facility is to eliminate sleeps from
-  the test suite. In most cases it should be possible to rewrite test
-  cases so that they do not need to sleep. (But this facility cannot
-  synchronize multiple processes.) However, to support test development,
-  and as a last resort, sync point waiting times out. There is a default
-  timeout, but it can be overridden:
-
-      SET DEBUG_SYNC= 'name WAIT_FOR sig TIMEOUT 10 EXECUTE 2';
-
-  TIMEOUT 0 is special: If the signal is not present, the wait times out
-  immediately.
-
-  When a wait timed out (even on TIMEOUT 0), a warning is generated so
-  that it shows up in the test result.
-
-  You can throw an error message and kill the query when a synchronization
-  point is hit a certain number of times:
-
-      SET DEBUG_SYNC= 'name HIT_LIMIT 3';
-
-  Or combine it with signal and/or wait:
-
-      SET DEBUG_SYNC= 'name SIGNAL sig EXECUTE 2 HIT_LIMIT 3';
-
-  Here the first two hits emit the signal, the third hit returns the error
-  message and kills the query.
-
-  For cases where you are not sure that an action is taken and thus
-  cleared in any case, you can force to clear (deactivate) a sync point:
-
-      SET DEBUG_SYNC= 'name CLEAR';
-
-  If you want to clear all actions and clear the global signal, use:
-
-      SET DEBUG_SYNC= 'RESET';
-
-  This is the only way to reset the global signal to an empty string.
-
-  For testing of the facility itself you can execute a sync point just
-  as if it had been hit:
-
-      SET DEBUG_SYNC= 'name TEST';
-
-
-  === Formal Syntax ===
-
-  The string to "assign" to the DEBUG_SYNC variable can contain:
-
-      {RESET |
-       <sync point name> TEST |
-       <sync point name> CLEAR |
-       <sync point name> {{SIGNAL <signal name> |
-                           WAIT_FOR <signal name> [TIMEOUT <seconds>]}
-                          [EXECUTE <count>] &| HIT_LIMIT <count>}
-
-  Here '&|' means 'and/or'. This means that one of the sections
-  separated by '&|' must be present or both of them.
-
-
-  === Activation/Deactivation ===
-
-  The facility is an optional part of the MySQL server.
-  It is enabled in a debug server by default.
-
-      ./configure --enable-debug-sync
-
-  The Debug Sync Facility, when compiled in, is disabled by default. It
-  can be enabled by a mysqld command line option:
-
-      --debug-sync-timeout[=default_wait_timeout_value_in_seconds]
-
-  'default_wait_timeout_value_in_seconds' is the default timeout for the
-  WAIT_FOR action. If set to zero, the facility stays disabled.
-
-  The facility is enabled by default in the test suite, but can be
-  disabled with:
-
-      mysql-test-run.pl ... --debug-sync-timeout=0 ...
-
-  Likewise the default wait timeout can be set:
-
-      mysql-test-run.pl ... --debug-sync-timeout=10 ...
-
-  The command line option influences the readable value of the system
-  variable 'debug_sync'.
-
-  * If the facility is not compiled in, the system variable does not exist.
-
-  * If --debug-sync-timeout=0 the value of the variable reads as "OFF".
-
-  * Otherwise the value reads as "ON - current signal: " followed by the
-    current signal string, which can be empty.
-
-  The readable variable value is the same, regardless if read as global
-  or session value.
-
-  Setting the 'debug-sync' system variable requires 'SUPER' privilege.
-  You can never read back the string that you assigned to the variable,
-  unless you assign the value that the variable does already have. But
-  that would give a parse error. A syntactically correct string is
-  parsed into a debug sync action and stored apart from the variable value.
-
-
-  === Implementation ===
-
-  Pseudo code for a sync point:
-
-      #define DEBUG_SYNC(thd, sync_point_name)
-                if (unlikely(opt_debug_sync_timeout))
-                  debug_sync(thd, STRING_WITH_LEN(sync_point_name))
-
-  The sync point performs a binary search in a sorted array of actions
-  for this thread.
-
-  The SET DEBUG_SYNC statement adds a requested action to the array or
-  overwrites an existing action for the same sync point. When it adds a
-  new action, the array is sorted again.
-
-
-  === A typical synchronization pattern ===
-
-  There are quite a few places in MySQL, where we use a synchronization
-  pattern like this:
-
-  mysql_mutex_lock(&mutex);
-  thd->enter_cond(&condition_variable, &mutex, new_message);
-  #if defined(ENABLE_DEBUG_SYNC)
-  if (!thd->killed && !end_of_wait_condition)
-     DEBUG_SYNC(thd, "sync_point_name");
-  #endif
-  while (!thd->killed && !end_of_wait_condition)
-    mysql_cond_wait(&condition_variable, &mutex);
-  thd->exit_cond(old_message);
-
-  Here some explanations:
-
-  thd->enter_cond() is used to register the condition variable and the
-  mutex in thd->mysys_var. This is done to allow the thread to be
-  interrupted (killed) from its sleep. Another thread can find the
-  condition variable to signal and mutex to use for synchronization in
-  this thread's THD::mysys_var.
-
-  thd->enter_cond() requires the mutex to be acquired in advance.
-
-  thd->exit_cond() unregisters the condition variable and mutex and
-  releases the mutex.
-
-  If you want to have a Debug Sync point with the wait, please place it
-  behind enter_cond(). Only then you can safely decide, if the wait will
-  be taken. Also you will have THD::proc_info correct when the sync
-  point emits a signal. DEBUG_SYNC sets its own proc_info, but restores
-  the previous one before releasing its internal mutex. As soon as
-  another thread sees the signal, it does also see the proc_info from
-  before entering the sync point. In this case it will be "new_message",
-  which is associated with the wait that is to be synchronized.
-
-  In the example above, the wait condition is repeated before the sync
-  point. This is done to skip the sync point, if no wait takes place.
-  The sync point is before the loop (not inside the loop) to have it hit
-  once only. It is possible that the condition variable is signaled
-  multiple times without the wait condition to be true.
-
-  A bit off-topic: At some places, the loop is taken around the whole
-  synchronization pattern:
-
-  while (!thd->killed && !end_of_wait_condition)
-  {
-    mysql_mutex_lock(&mutex);
-    thd->enter_cond(&condition_variable, &mutex, new_message);
-    if (!thd->killed [&& !end_of_wait_condition])
-    {
-      [DEBUG_SYNC(thd, "sync_point_name");]
-      mysql_cond_wait(&condition_variable, &mutex);
-    }
-    thd->exit_cond(old_message);
-  }
-
-  Note that it is important to repeat the test for thd->killed after
-  enter_cond(). Otherwise the killing thread may kill this thread after
-  it tested thd->killed in the loop condition and before it registered
-  the condition variable and mutex in enter_cond(). In this case, the
-  killing thread does not know that this thread is going to wait on a
-  condition variable. It would just set THD::killed. But if we would not
-  test it again, we would go asleep though we are killed. If the killing
-  thread would kill us when we are after the second test, but still
-  before sleeping, we hold the mutex, which is registered in mysys_var.
-  The killing thread would try to acquire the mutex before signaling
-  the condition variable. Since the mutex is only released implicitly in
-  mysql_cond_wait(), the signaling happens at the right place. We
-  have a safe synchronization.
-
-  === Co-work with the DBUG facility ===
-
-  When running the MySQL test suite with the --debug-dbug command line
-  option, the Debug Sync Facility writes trace messages to the DBUG
-  trace. The following shell commands proved very useful in extracting
-  relevant information:
-
-  egrep 'query:|debug_sync_exec:' mysql-test/var/log/mysqld.1.trace
-
-  It shows all executed SQL statements and all actions executed by
-  synchronization points.
-
-  Sometimes it is also useful to see, which synchronization points have
-  been run through (hit) with or without executing actions. Then add
-  "|debug_sync_point:" to the egrep pattern.
-
-  === Further reading ===
-
-  For a discussion of other methods to synchronize threads see
-  http://forge.mysql.com/wiki/MySQL_Internals_Test_Synchronization
-
-  For complete syntax tests, functional tests, and examples see the test
-  case debug_sync.test.
-
-  See also worklog entry WL#4259 - Test Synchronization Facility
-*/
+/* see include/mysql/service_debug_sync.h for debug sync documentation */
 
 #include "debug_sync.h"
 
@@ -382,57 +82,16 @@ struct st_debug_sync_globals
 };
 static st_debug_sync_globals debug_sync_global; /* All globals in one object */
 
-/**
-  Callback pointer for C files.
-*/
-extern "C" void (*debug_sync_C_callback_ptr)(const char *, size_t);
+extern uint opt_debug_sync_timeout;
 
 /**
   Callbacks from C files.
 */
 C_MODE_START
-static void debug_sync_C_callback(const char *, size_t);
+static void debug_sync(THD *thd, const char *sync_point_name, size_t name_len);
 static int debug_sync_qsort_cmp(const void *, const void *);
 C_MODE_END
 
-/**
-  Callback for debug sync, to be used by C files. See thr_lock.c for example.
-
-  @description
-
-    We cannot place a sync point directly in C files (like those in mysys or
-    certain storage engines written mostly in C like MyISAM or Maria). Because
-    they are C code and do not include sql_priv.h. So they do not know the
-    macro DEBUG_SYNC(thd, sync_point_name). The macro needs a 'thd' argument.
-    Hence it cannot be used in files outside of the sql/ directory.
-
-    The workaround is to call back simple functions like this one from
-    non-sql/ files.
-
-    We want to allow modules like thr_lock to be used without sql/ and
-    especially without Debug Sync. So we cannot just do a simple call
-    of the callback function. Instead we provide a global pointer in
-    the other file, which is to be set to the callback by Debug Sync.
-    If the pointer is not set, no call back will be done. If Debug
-    Sync sets the pointer to a callback function like this one, it will
-    be called. That way thr_lock.c does not have an undefined reference
-    to Debug Sync and can be used without it. Debug Sync, in contrast,
-    has an undefined reference to that pointer and thus requires
-    thr_lock to be linked too. But this is not a problem as it is part
-    of the MySQL server anyway.
-
-  @note
-    The callback pointer in C files is set only if debug sync is
-    initialized. And this is done only if opt_debug_sync_timeout is set.
-*/
-
-static void debug_sync_C_callback(const char *sync_point_name,
-                                  size_t name_len)
-{
-  if (unlikely(opt_debug_sync_timeout))
-    debug_sync(current_thd, sync_point_name, name_len);
-}
-
 #ifdef HAVE_PSI_INTERFACE
 static PSI_mutex_key key_debug_sync_globals_ds_mutex;
 
@@ -495,7 +154,7 @@ int debug_sync_init(void)
       DBUG_RETURN(rc); /* purecov: inspected */
 
     /* Set the call back pointer in C files. */
-    debug_sync_C_callback_ptr= debug_sync_C_callback;
+    debug_sync_C_callback_ptr= debug_sync;
   }
 
   DBUG_RETURN(0);
@@ -1857,12 +1516,14 @@ static void debug_sync_execute(THD *thd, st_debug_sync_action *action)
   @param[in]     name_len           length of sync point name
 */
 
-void debug_sync(THD *thd, const char *sync_point_name, size_t name_len)
+static void debug_sync(THD *thd, const char *sync_point_name, size_t name_len)
 {
+  if (!thd)
+    thd= current_thd;
+
   st_debug_sync_control *ds_control= thd->debug_sync_control;
   st_debug_sync_action  *action;
   DBUG_ENTER("debug_sync");
-  DBUG_ASSERT(thd);
   DBUG_ASSERT(sync_point_name);
   DBUG_ASSERT(name_len);
   DBUG_ASSERT(ds_control);
diff --git a/sql/debug_sync.h b/sql/debug_sync.h
index 50881f491fe..4d29d6e7508 100644
--- a/sql/debug_sync.h
+++ b/sql/debug_sync.h
@@ -32,15 +32,6 @@ class THD;
 
 #if defined(ENABLED_DEBUG_SYNC)
 
-/* Macro to be put in the code at synchronization points. */
-#define DEBUG_SYNC(_thd_, _sync_point_name_)                            \
-          do { if (unlikely(opt_debug_sync_timeout))                    \
-               debug_sync(_thd_, STRING_WITH_LEN(_sync_point_name_));   \
-             } while (0)
-
-/* Command line option --debug-sync-timeout. See mysqld.cc. */
-extern MYSQL_PLUGIN_IMPORT uint opt_debug_sync_timeout;
-
 /* Default WAIT_FOR timeout if command line option is given without argument. */
 #define DEBUG_SYNC_DEFAULT_WAIT_TIMEOUT 300
 
@@ -49,13 +40,8 @@ extern int  debug_sync_init(void);
 extern void debug_sync_end(void);
 extern void debug_sync_init_thread(THD *thd);
 extern void debug_sync_end_thread(THD *thd);
-extern void debug_sync(THD *thd, const char *sync_point_name, size_t name_len);
 extern bool debug_sync_set_action(THD *thd, const char *action_str, size_t len);
 
-#else /* defined(ENABLED_DEBUG_SYNC) */
-
-#define DEBUG_SYNC(_thd_, _sync_point_name_)    /* disabled DEBUG_SYNC */
-
 #endif /* defined(ENABLED_DEBUG_SYNC) */
 
 #endif /* DEBUG_SYNC_INCLUDED */
diff --git a/sql/slave.cc b/sql/slave.cc
index cf550ac22e3..ac7c9cd8c9e 100644
--- a/sql/slave.cc
+++ b/sql/slave.cc
@@ -1339,7 +1339,7 @@ static int get_master_version_and_clock(MYSQL* mysql, Master_info* mi)
                     const char act[]=
                       "now "
                       "wait_for signal.get_unix_timestamp";
-                    DBUG_ASSERT(opt_debug_sync_timeout > 0);
+                    DBUG_ASSERT(debug_sync_service);
                     DBUG_ASSERT(!debug_sync_set_action(current_thd,
                                                        STRING_WITH_LEN(act)));
                   };);
@@ -1389,7 +1389,7 @@ static int get_master_version_and_clock(MYSQL* mysql, Master_info* mi)
                     const char act[]=
                       "now "
                       "wait_for signal.get_server_id";
-                    DBUG_ASSERT(opt_debug_sync_timeout > 0);
+                    DBUG_ASSERT(debug_sync_service);
                     DBUG_ASSERT(!debug_sync_set_action(current_thd, 
                                                        STRING_WITH_LEN(act)));
                   };);
@@ -3034,7 +3034,7 @@ connected:
                       const char act[]=
                         "now "
                         "wait_for signal.io_thread_let_running";
-                      DBUG_ASSERT(opt_debug_sync_timeout > 0);
+                      DBUG_ASSERT(debug_sync_service);
                       DBUG_ASSERT(!debug_sync_set_action(thd, 
                                                          STRING_WITH_LEN(act)));
                     };);
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 90f6f0264a7..70258629197 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -2934,7 +2934,7 @@ end_with_restore_list:
                       const char act2[]=
                         "now "
                         "signal signal.continued";
-                      DBUG_ASSERT(opt_debug_sync_timeout > 0);
+                      DBUG_ASSERT(debug_sync_service);
                       DBUG_ASSERT(!debug_sync_set_action(thd,
                                                          STRING_WITH_LEN(act1)));
                       DBUG_ASSERT(!debug_sync_set_action(thd,
diff --git a/sql/sql_plugin.cc b/sql/sql_plugin.cc
index 5f196e59c6f..067690ea06f 100644
--- a/sql/sql_plugin.cc
+++ b/sql/sql_plugin.cc
@@ -1520,6 +1520,10 @@ int plugin_init(int *argc, char **argv, int flags)
       goto err;
   }
 
+  /* prepare debug_sync service */
+  DBUG_ASSERT(strcmp(list_of_services[5].name, "debug_sync_service") == 0);
+  list_of_services[5].service= *(void**)&debug_sync_C_callback_ptr;
+
   mysql_mutex_lock(&LOCK_plugin);
 
   initialized= 1;
diff --git a/sql/sql_plugin_services.h b/sql/sql_plugin_services.h
index e6302f6d345..c779547059d 100644
--- a/sql/sql_plugin_services.h
+++ b/sql/sql_plugin_services.h
@@ -61,5 +61,6 @@ static struct st_service_ref list_of_services[]=
   { "thd_wait_service",    VERSION_thd_wait,    &thd_wait_handler },
   { "my_thread_scheduler_service", VERSION_my_thread_scheduler, &my_thread_scheduler_handler },
   { "progress_report_service", VERSION_progress_report, &progress_report_handler },
+  { "debug_sync_service", VERSION_debug_sync, 0 } // updated in plugin_init()
 };
 
diff --git a/sql/sql_repl.cc b/sql/sql_repl.cc
index 199afb30344..b5c852f9b29 100644
--- a/sql/sql_repl.cc
+++ b/sql/sql_repl.cc
@@ -904,7 +904,7 @@ impossible position";
                           const char act[]=
                             "now "
                             "wait_for signal.continue";
-                          DBUG_ASSERT(opt_debug_sync_timeout > 0);
+                          DBUG_ASSERT(debug_sync_service);
                           DBUG_ASSERT(!debug_sync_set_action(thd,
                                                              STRING_WITH_LEN(act)));
                           const char act2[]=