Add max dsp load API (#1007)

* Implement jack_max_cpu_load

Signed-off-by: falkTX <falktx@falktx.com>

* Bump version

Signed-off-by: falkTX <falktx@falktx.com>

* Fix JackEngineControl::CalcCPULoad for max value

Signed-off-by: falkTX <falktx@falktx.com>

* Fix function comment

Signed-off-by: falkTX <falktx@falktx.com>

* Add changelog entry

Signed-off-by: falkTX <falktx@falktx.com>

---------

Signed-off-by: falkTX <falktx@falktx.com>

ChangeLog.rst

@@ -1,6 +1,10 @@
 ChangeLog
 #########
 
+* 1.9.23 (WIP)
+
+  * Add jack_max_cpu_load API call
+
 * 1.9.22 (2023-02-02)
 
   * The waf autooption ``--example-tools`` has been removed.

common/JackAPI.cpp

@@ -195,6 +195,7 @@ extern "C"
                                         jack_time_t    *next_usecs,
                                         float          *period_usecs);
     LIB_EXPORT float jack_cpu_load(jack_client_t *client);
+    LIB_EXPORT float jack_max_cpu_load(jack_client_t *client);
     LIB_EXPORT jack_native_thread_t jack_client_thread_id(jack_client_t *);
     LIB_EXPORT void jack_set_error_function(print_function);
     LIB_EXPORT void jack_set_info_function(print_function);
@@ -1457,6 +1458,20 @@ LIB_EXPORT float jack_cpu_load(jack_client_t* ext_client)
     }
 }
 
+LIB_EXPORT float jack_max_cpu_load(jack_client_t* ext_client)
+{
+    JackGlobals::CheckContext("jack_max_cpu_load");
+
+    JackClient* client = (JackClient*)ext_client;
+    if (client == NULL) {
+        jack_error("jack_max_cpu_load called with a NULL client");
+        return 0.0f;
+    } else {
+        JackEngineControl* control = GetEngineControl();
+        return (control ? control->fMaxCPULoad : 0.0f);
+    }
+}
+
 LIB_EXPORT jack_native_thread_t jack_client_thread_id(jack_client_t* ext_client)
 {
     JackGlobals::CheckContext("jack_client_thread_id");

common/JackEngineControl.cpp

@@ -63,7 +63,7 @@ void JackEngineControl::CalcCPULoad(JackClientInterface** table,
 
     // Each time we have a full set of iterations, recompute the current
     // usage from the latest JACK_ENGINE_ROLLING_COUNT client entries.
-    if (fRollingClientUsecsCnt && (fRollingClientUsecsIndex == 0)) {
+    if (fRollingClientUsecsCnt && (fRollingClientUsecsIndex == 0 || fRollingClientUsecsCnt == fRollingInterval)) {
         jack_time_t avg_usecs = 0;
         jack_time_t max_usecs = 0;
 
@@ -74,6 +74,12 @@ void JackEngineControl::CalcCPULoad(JackClientInterface** table,
 
         fMaxUsecs = JACK_MAX(fMaxUsecs, max_usecs);
 
+        if (fRollingClientUsecsCnt == fRollingInterval)
+        {
+            fMaxUsecs = max_usecs;
+            fRollingClientUsecsCnt = 0;
+        }
+
         if (max_usecs < ((fPeriodUsecs * 95) / 100)) {
             // Average the values from our JACK_ENGINE_ROLLING_COUNT array
             fSpareUsecs = (jack_time_t)(fPeriodUsecs - (avg_usecs / JACK_ENGINE_ROLLING_COUNT));
@@ -83,6 +89,7 @@ void JackEngineControl::CalcCPULoad(JackClientInterface** table,
         }
 
         fCPULoad = ((1.f - (float(fSpareUsecs) / float(fPeriodUsecs))) * 50.f + (fCPULoad * 0.5f));
+        fMaxCPULoad = (1.f - float(fMaxUsecs < fPeriodUsecs ? fPeriodUsecs - fMaxUsecs : 0) / float(fPeriodUsecs)) * 100.f;
     }
 
     fRollingClientUsecsCnt++;

common/JackEngineControl.h

@@ -76,9 +76,10 @@ struct SERVER_EXPORT JackEngineControl : public JackShmMem
     jack_time_t fMaxUsecs;
     jack_time_t fRollingClientUsecs[JACK_ENGINE_ROLLING_COUNT];
     unsigned int fRollingClientUsecsCnt;
-    int	fRollingClientUsecsIndex;
-    int	fRollingInterval;
+    unsigned int fRollingClientUsecsIndex;
+    unsigned int fRollingInterval;
     float fCPULoad;
+    float fMaxCPULoad;
 
     // For OSX thread
     UInt64 fPeriod;
@@ -124,6 +125,7 @@ struct SERVER_EXPORT JackEngineControl : public JackShmMem
         strncpy(fServerName, server_name, sizeof(fServerName));
         fServerName[sizeof(fServerName) - 1] = 0;
         fCPULoad = 0.f;
+        fMaxCPULoad = 0.f;
         fPeriod = 0;
         fComputation = 0;
         fConstraint = 0;

common/jack/jack.h

@@ -704,6 +704,14 @@ int jack_engine_takeover_timebase (jack_client_t *) JACK_OPTIONAL_WEAK_DEPRECATE
  */
 float jack_cpu_load (jack_client_t *client) JACK_OPTIONAL_WEAK_EXPORT;
 
+/**
+ * @return the current maximum CPU load used by JACK.  This is the
+ * total time it takes to execute a full process cycle for all clients
+ * as a percentage of the real time available per cycle determined
+ * by the buffer size and sample rate.
+ */
+float jack_max_cpu_load (jack_client_t *client) JACK_OPTIONAL_WEAK_EXPORT;
+
 /**@}*/
 
 /**

wscript

@@ -10,7 +10,7 @@ from waflib import Logs, Options, TaskGen
 from waflib.Build import BuildContext, CleanContext, InstallContext, UninstallContext
 
 # see also common/JackConstants.h
-VERSION = '1.9.22'
+VERSION = '1.9.23'
 APPNAME = 'jack'
 JACK_API_VERSION = '0.1.0'