From 632a1785e4a9965082421c9a710f3606807d0548 Mon Sep 17 00:00:00 2001
From: Dvir Volk <dvirsky@gmail.com>
Date: Sun, 2 Jul 2017 16:57:16 +0300
Subject: [PATCH] added periodic task runner

---
 rmutil/periodic.c      | 76 ++++++++++++++++++++++++++++++++++++++++++
 rmutil/periodic.h      | 27 +++++++++++++++
 rmutil/test_periodic.c | 27 +++++++++++++++
 3 files changed, 130 insertions(+)
 create mode 100644 rmutil/periodic.c
 create mode 100644 rmutil/periodic.h
 create mode 100644 rmutil/test_periodic.c

diff --git a/rmutil/periodic.c b/rmutil/periodic.c
new file mode 100644
index 0000000..3cdd997
--- /dev/null
+++ b/rmutil/periodic.c
@@ -0,0 +1,76 @@
+#include "periodic.h"
+#include <pthread.h>
+#include <stdlib.h>
+#include <errno.h>
+
+typedef struct RMUtilTimer {
+  RMutilTimerFunc cb;
+  void *privdata;
+  struct timespec interval;
+  pthread_t thread;
+  pthread_mutex_t lock;
+  pthread_cond_t cond;
+} RMUtilTimer;
+
+static struct timespec timespecAdd(struct timespec *a, struct timespec *b) {
+  struct timespec ret;
+  ret.tv_sec = a->tv_sec + b->tv_sec;
+
+  long long ns = a->tv_nsec + b->tv_nsec;
+  ret.tv_sec += ns / 1000000000;
+  ret.tv_nsec = ns % 1000000000;
+  return ret;
+}
+
+static void *rmutilTimer_Loop(void *ctx) {
+  RMUtilTimer *tm = ctx;
+
+  int rc = ETIMEDOUT;
+  struct timespec ts;
+
+  pthread_mutex_lock(&tm->lock);
+  while (rc != 0) {
+    clock_gettime(CLOCK_REALTIME, &ts);
+    struct timespec timeout = timespecAdd(&ts, &tm->interval);
+    if ((rc = pthread_cond_timedwait(&tm->cond, &tm->lock, &timeout)) == ETIMEDOUT) {
+
+      // Create a thread safe context if we're running inside redis
+      RedisModuleCtx *rctx = NULL;
+      if (RedisModule_GetThreadSafeContext) rctx = RedisModule_GetThreadSafeContext(NULL);
+
+      // call our callback...
+      tm->cb(rctx, tm->privdata);
+
+      // If needed - free the thread safe context.
+      // It's up to the user to decide whether automemory is active there
+      if (rctx) RedisModule_FreeThreadSafeContext(rctx);
+    }
+  }
+  //  RedisModule_Log(tm->redisCtx, "notice", "Timer cancelled");
+
+  return NULL;
+}
+
+RMUtilTimer *RMUtil_NewPeriodicTimer(RMutilTimerFunc cb, void *privdata, struct timespec interval) {
+  RMUtilTimer *ret = malloc(sizeof(*ret));
+  *ret = (RMUtilTimer){
+      .privdata = privdata, .interval = interval, .cb = cb,
+  };
+  pthread_cond_init(&ret->cond, NULL);
+  pthread_mutex_init(&ret->lock, NULL);
+
+  pthread_create(&ret->thread, NULL, rmutilTimer_Loop, ret);
+  return ret;
+}
+
+int RMUtilTimer_Stop(RMUtilTimer *t) {
+  int rc;
+  if (0 == (rc = pthread_cond_signal(&t->cond))) {
+    rc = pthread_join(t->thread, NULL);
+  }
+  return rc;
+}
+
+void RMUtilTimer_Free(RMUtilTimer *t) {
+  free(t);
+}
diff --git a/rmutil/periodic.h b/rmutil/periodic.h
new file mode 100644
index 0000000..ddd2aa8
--- /dev/null
+++ b/rmutil/periodic.h
@@ -0,0 +1,27 @@
+#ifndef RMUTIL_PERIODIC_H_
+#define RMUTIL_PERIODIC_H_
+#include <time.h>
+#include <redismodule.h>
+
+/** periodic.h - Utility periodic timer running a task repeatedly every given time interval */
+
+/* RMUtilTimer - opaque context for the timer */
+struct RMUtilTimer;
+
+/* RMutilTimerFunc - callback type for timer tasks. The ctx is a thread-safe redis module context
+ * that should be locked/unlocked by the callback when running stuff against redis. privdata is
+ * pre-existing private data */
+typedef void (*RMutilTimerFunc)(RedisModuleCtx *ctx, void *privdata);
+
+/* Create and start a new periodic timer. Each timer has its own thread and can only be run and
+ * stopped once. The timer runs `cb` every `interval` with `privdata` passed to the callback. */
+struct RMUtilTimer *RMUtil_NewPeriodicTimer(RMutilTimerFunc cb, void *privdata,
+                                            struct timespec interval);
+
+/* Stop the timer loop. This should return immediately and join the thread */
+int RMUtilTimer_Stop(struct RMUtilTimer *t);
+
+/* Free the timer context. The caller should be responsible for freeing the private data at this
+ * point */
+void RMUtilTimer_Free(struct RMUtilTimer *t);
+#endif
\ No newline at end of file
diff --git a/rmutil/test_periodic.c b/rmutil/test_periodic.c
new file mode 100644
index 0000000..030a021
--- /dev/null
+++ b/rmutil/test_periodic.c
@@ -0,0 +1,27 @@
+#include <stdio.h>
+#include <redismodule.h>
+#include <unistd.h>
+#include "periodic.h"
+#include "assert.h"
+#include "test.h"
+
+void timerCb(RedisModuleCtx *ctx, void *p) {
+  int *x = p;
+  (*x)++;
+}
+
+int testPeriodic() {
+  int x = 0;
+  struct RMUtilTimer *tm =
+      RMUtil_NewPeriodicTimer(timerCb, &x, (struct timespec){.tv_sec = 0, .tv_nsec = 10000000});
+
+  sleep(1);
+
+  ASSERT_EQUAL(0, RMUtilTimer_Stop(tm));
+  ASSERT(x > 0);
+  ASSERT(x <= 100);
+  RMUtilTimer_Free(tm);
+  return 0;
+}
+
+TEST_MAIN({ TESTFUNC(testPeriodic); });