eventloop: support sub-millisecond timer resolution

Timeouts may now be specified in fractions of milliseconds. e.g.  after 0.5

This can be useful on faster systems where 1ms resolution is too coarse.

Also, use clock_gettime(CLOCK_MONOTONIC_RAW) for timers, if available.
This clock is insensitive to system clock changes and ntp adjustments.

Signed-off-by: Steve Bennett <steveb@workware.net.au>

1 files changed, 47 insertions, 32 deletions

diff --git a/jim-eventloop.c b/jim-eventloop.c
index 1b1de47..cea5d9e 100644
--- a/jim-eventloop.c
+++ b/jim-eventloop.c
@@ -54,20 +54,19 @@
 #if defined(__MINGW32__)
 #include <windows.h>
 #include <winsock.h>
-#define msleep Sleep
+#define usleep(US) Sleep((US) / 1000)
+#define HAVE_USLEEP
 #else
 #include <sys/types.h>
 #ifdef HAVE_SYS_SELECT_H
 #include <sys/select.h>
 #endif
+#endif
 
 #ifndef HAVE_USLEEP
 /* XXX: Implement this in terms of select() or nanosleep() */
-#define msleep(MS) sleep((MS) / 1000)
+#define usleep(US) sleep((US) / 1000000)
 #warning "sub-second sleep not supported"
-#else
-#define msleep(MS) sleep((MS) / 1000); usleep(((MS) % 1000) * 1000);
-#endif
 #endif
 
 /* --- */
@@ -87,8 +86,8 @@ typedef struct Jim_FileEvent
 typedef struct Jim_TimeEvent
 {
     jim_wide id;                /* time event identifier. */
-    long initialms;             /* initial relative timer value */
-    jim_wide when;              /* milliseconds */
+    jim_wide initialus;         /* initial relative timer value in microseconds */
+    jim_wide when;              /* microseconds */
     Jim_TimeProc *timeProc;
     Jim_EventFinalizerProc *finalizerProc;
     void *clientData;
@@ -189,28 +188,43 @@ void Jim_DeleteFileHandler(Jim_Interp *interp, int fd, int mask)
 }
 
 /**
- * Returns the time since interp creation in milliseconds.
+ * Returns the time since interp creation in microseconds.
  */
-static jim_wide JimGetTime(Jim_EventLoop *eventLoop)
+static jim_wide JimGetTimeUsec(Jim_EventLoop *eventLoop)
 {
+    long long now;
     struct timeval tv;
 
-    gettimeofday(&tv, NULL);
+#if defined(HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC_RAW)
+    struct timespec ts;
+
+    if (clock_gettime(CLOCK_MONOTONIC_RAW, &ts) == 0) {
+        now = ts.tv_sec * 1000000LL + ts.tv_nsec / 1000;
+    }
+    else
+#endif
+    {
+        gettimeofday(&tv, NULL);
+
+        now = tv.tv_sec * 1000000LL + tv.tv_usec;
+    }
 
-    return (jim_wide)(tv.tv_sec - eventLoop->timeBase) * 1000 + tv.tv_usec / 1000;
+    return now - eventLoop->timeBase;
 }
 
-jim_wide Jim_CreateTimeHandler(Jim_Interp *interp, jim_wide milliseconds,
+jim_wide Jim_CreateTimeHandler(Jim_Interp *interp, jim_wide us,
     Jim_TimeProc * proc, void *clientData, Jim_EventFinalizerProc * finalizerProc)
 {
     Jim_EventLoop *eventLoop = Jim_GetAssocData(interp, "eventloop");
     jim_wide id = ++eventLoop->timeEventNextId;
     Jim_TimeEvent *te, *e, *prev;
 
+    printf("Create time handler, us=%lld, now=%lld\n", us, JimGetTimeUsec(eventLoop));
+
     te = Jim_Alloc(sizeof(*te));
     te->id = id;
-    te->initialms = milliseconds;
-    te->when = JimGetTime(eventLoop) + milliseconds;
+    te->initialus = us;
+    te->when = JimGetTimeUsec(eventLoop) + us;
     te->timeProc = proc;
     te->finalizerProc = finalizerProc;
     te->clientData = clientData;
@@ -311,7 +325,7 @@ jim_wide Jim_DeleteTimeHandler(Jim_Interp *interp, jim_wide id)
     if (te) {
         jim_wide remain;
 
-        remain = te->when - JimGetTime(eventLoop);
+        remain = te->when - JimGetTimeUsec(eventLoop);
         remain = (remain < 0) ? 0 : remain;
 
         Jim_FreeTimeHandler(interp, te);
@@ -338,7 +352,7 @@ jim_wide Jim_DeleteTimeHandler(Jim_Interp *interp, jim_wide id)
  */
 int Jim_ProcessEvents(Jim_Interp *interp, int flags)
 {
-    jim_wide sleep_ms = -1;
+    jim_wide sleep_us = -1;
     int processed = 0;
     Jim_EventLoop *eventLoop = Jim_GetAssocData(interp, "eventloop");
     Jim_FileEvent *fe = eventLoop->fileEventHead;
@@ -360,7 +374,7 @@ int Jim_ProcessEvents(Jim_Interp *interp, int flags)
 
     if (flags & JIM_DONT_WAIT) {
         /* Wait no time */
-        sleep_ms = 0;
+        sleep_us = 0;
     }
     else if (flags & JIM_TIME_EVENTS) {
         /* The nearest timer is always at the head of the list */
@@ -369,14 +383,14 @@ int Jim_ProcessEvents(Jim_Interp *interp, int flags)
 
             /* Calculate the time missing for the nearest
              * timer to fire. */
-            sleep_ms = shortest->when - JimGetTime(eventLoop);
-            if (sleep_ms < 0) {
-                sleep_ms = 0;
+            sleep_us = shortest->when - JimGetTimeUsec(eventLoop);
+            if (sleep_us < 0) {
+                sleep_us = 0;
             }
         }
         else {
             /* Wait forever */
-            sleep_ms = -1;
+            sleep_us = -1;
         }
     }
 
@@ -404,10 +418,10 @@ int Jim_ProcessEvents(Jim_Interp *interp, int flags)
             fe = fe->next;
         }
 
-        if (sleep_ms >= 0) {
+        if (sleep_us >= 0) {
             tvp = &tv;
-            tvp->tv_sec = sleep_ms / 1000;
-            tvp->tv_usec = 1000 * (sleep_ms % 1000);
+            tvp->tv_sec = sleep_us / 1000000;
+            tvp->tv_usec = sleep_us % 1000000;
         }
 
         retval = select(maxfd + 1, &rfds, &wfds, &efds, tvp);
@@ -456,8 +470,8 @@ int Jim_ProcessEvents(Jim_Interp *interp, int flags)
         }
     }
 #else
-    if (sleep_ms > 0) {
-        msleep(sleep_ms);
+    if (sleep_us > 0) {
+        usleep(sleep_us);
     }
 #endif
 
@@ -471,7 +485,7 @@ int Jim_ProcessEvents(Jim_Interp *interp, int flags)
             te = te->next;
             continue;
         }
-        if (JimGetTime(eventLoop) >= te->when) {
+        if (JimGetTimeUsec(eventLoop) >= te->when) {
             id = te->id;
             /* Remove from the list before executing */
             Jim_RemoveTimeHandler(eventLoop, id);
@@ -616,7 +630,8 @@ static void JimAfterTimeEventFinalizer(Jim_Interp *interp, void *clientData)
 static int JimELAfterCommand(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
 {
     Jim_EventLoop *eventLoop = Jim_CmdPrivData(interp);
-    jim_wide ms = 0, id;
+    double ms;
+    jim_wide id;
     Jim_Obj *objPtr, *idObjPtr;
     static const char * const options[] = {
         "cancel", "info", "idle", NULL
@@ -629,7 +644,7 @@ static int JimELAfterCommand(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
         Jim_WrongNumArgs(interp, 1, argv, "option ?arg ...?");
         return JIM_ERR;
     }
-    if (Jim_GetWide(interp, argv[1], &ms) != JIM_OK) {
+    if (Jim_GetDouble(interp, argv[1], &ms) != JIM_OK) {
         if (Jim_GetEnum(interp, argv[1], options, &option, "argument", JIM_ERRMSG) != JIM_OK) {
             return JIM_ERR;
         }
@@ -637,7 +652,7 @@ static int JimELAfterCommand(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
     }
     else if (argc == 2) {
         /* Simply a sleep */
-        msleep(ms);
+        usleep(ms * 1000);
         return JIM_OK;
     }
 
@@ -651,7 +666,7 @@ static int JimELAfterCommand(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
         case AFTER_CREATE: {
             Jim_Obj *scriptObj = Jim_ConcatObj(interp, argc - 2, argv + 2);
             Jim_IncrRefCount(scriptObj);
-            id = Jim_CreateTimeHandler(interp, ms, JimAfterTimeHandler, scriptObj,
+            id = Jim_CreateTimeHandler(interp, (jim_wide)(ms * 1000), JimAfterTimeHandler, scriptObj,
                 JimAfterTimeEventFinalizer);
             objPtr = Jim_NewStringObj(interp, NULL, 0);
             Jim_AppendString(interp, objPtr, "after#", -1);
@@ -709,7 +724,7 @@ static int JimELAfterCommand(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
                     if (e && e->timeProc == JimAfterTimeHandler) {
                         Jim_Obj *listObj = Jim_NewListObj(interp, NULL, 0);
                         Jim_ListAppendElement(interp, listObj, e->clientData);
-                        Jim_ListAppendElement(interp, listObj, Jim_NewStringObj(interp, e->initialms ? "timer" : "idle", -1));
+                        Jim_ListAppendElement(interp, listObj, Jim_NewStringObj(interp, e->initialus ? "timer" : "idle", -1));
                         Jim_SetResult(interp, listObj);
                         return JIM_OK;
                     }