From: bert hubert <bert.hubert@netherlabs.nl>
Date: Fri, 5 Jun 2015 19:21:46 +0000 (+0200)
Subject: make timeout a double, since we'd busy loop otherwise on sub-msec intervals, plus... 
X-Git-Tag: dnsdist-1.0.0-alpha1~248^2~78^2~19^2^2~9
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=ce79dd66774e3a6a44b8d8b386a0b4d443b9a9e3;p=pdns

make timeout a double, since we'd busy loop otherwise on sub-msec intervals, plus fix testcase which was actually a race condition.
---

diff --git a/pdns/delaypipe.cc b/pdns/delaypipe.cc
index d0798a532..046a90ef3 100644
--- a/pdns/delaypipe.cc
+++ b/pdns/delaypipe.cc
@@ -50,16 +50,18 @@ bool ObjectPipe<T>::read(T* t)
 }
 
 template<class T>
-int ObjectPipe<T>::readTimeout(T* t, int msec)
+int ObjectPipe<T>::readTimeout(T* t, double msec)
 {
   T* ptr;
-  int ret = waitForData(d_fds[0], 0, 1000*msec);
-  if(ret <0)
-    unixDie("waiting for data in object pipe");
-  if(ret == 0) 
-    return -1;
+  if(msec != 0) {
+    int ret = waitForData(d_fds[0], 0, 1000*msec);
+    if(ret < 0)
+      unixDie("waiting for data in object pipe");
+    if(ret == 0) 
+      return -1;
+  }
 
-  ret = ::read(d_fds[0], &ptr, sizeof(ptr));
+  int ret = ::read(d_fds[0], &ptr, sizeof(ptr));
 
   if(ret < 0)
     unixDie("read");
@@ -97,31 +99,46 @@ DelayPipe<T>::~DelayPipe()
   d_thread.join();
 }
 
+
+
 template<class T>
 void DelayPipe<T>::worker()
 {
   Combo c;
   for(;;) {
-    int ret = d_pipe.readTimeout(&c, 10); // XXXX NEEDS TO BE DYNAMIC
-    if(ret > 0) {  // we got an object
-      d_work.insert(make_pair(c.when, c.what));
-    }
-    else if(ret==0) { // timeout
-
-      break;
+    double delay=-1;  // infinite
+    struct timespec now;
+    if(!d_work.empty()) {
+      clock_gettime(CLOCK_MONOTONIC, &now);
+      delay=1000*tsdelta(d_work.begin()->first, now);
+      if(delay < 0) {
+	delay=0;   // don't wait
+      }
     }
-    else {
-      //      cout<<"Got a timeout"<<endl;
+    if(delay != 0 ) {
+      int ret = d_pipe.readTimeout(&c, delay); 
+      if(ret > 0) {  // we got an object
+	d_work.insert(make_pair(c.when, c.what));
+      }
+      else if(ret==0) { // EOF
+	break;
+      }
+      else {
+	;
+      }
+      clock_gettime(CLOCK_MONOTONIC, &now);
     }
-    struct timespec now;
-    clock_gettime(CLOCK_MONOTONIC, &now);
+
     tscomp cmp;
+
     for(auto iter = d_work.begin() ; iter != d_work.end(); ) { // do the needful
       if(cmp(iter->first, now)) {
 	iter->second();
 	d_work.erase(iter++);
       }
-      else break;
+      else {
+	break;
+      }
     }
   }
 }
diff --git a/pdns/delaypipe.hh b/pdns/delaypipe.hh
index cfc72e74b..80cca5906 100644
--- a/pdns/delaypipe.hh
+++ b/pdns/delaypipe.hh
@@ -23,7 +23,7 @@ public:
   ~ObjectPipe();
   void write(T& t);
   bool read(T* t); // returns false on EOF
-  int readTimeout(T* t, int msec); // -1 is timeout, 0 is no data, 1 is data
+  int readTimeout(T* t, double msec); // -1 is timeout, 0 is no data, 1 is data
   void close(); 
 private:
   int d_fds[2];
@@ -46,6 +46,11 @@ private:
     struct timespec when;
   };
 
+  double tsdelta(const struct timespec& a, const struct timespec& b) // read as a-b
+  {
+    return 1.0*(a.tv_sec-b.tv_sec)+1.0*(a.tv_nsec-b.tv_nsec)/1000000000.0;
+  }
+
   ObjectPipe<Combo> d_pipe;
   struct tscomp {
     bool operator()(const struct timespec& a, const struct timespec& b) const
diff --git a/pdns/test-delaypipe_hh.cc b/pdns/test-delaypipe_hh.cc
index 94287a935..145adc4cb 100644
--- a/pdns/test-delaypipe_hh.cc
+++ b/pdns/test-delaypipe_hh.cc
@@ -46,7 +46,7 @@ BOOST_AUTO_TEST_CASE(test_delay_pipe) {
 
   for(; n < 10; ++n) {
     Work w{n};
-    dp.submit(w, 1000);
+    dp.submit(w, 1200);
   }
   sleep(1);
   BOOST_CHECK_EQUAL(done, 5);