naively implement timeout for waitpid (arangodb#9943)

jsteemann · KVS85 · KVS85 · commit 844809e3f312 · 2020-01-14T17:53:20.000+03:00
Co-authored-by: KVS85 &lt;vadim@arangodb.com&gt;
diff --git a/lib/Basics/process-utils.cpp b/lib/Basics/process-utils.cpp
@@ -34,6 +34,7 @@
 #include <type_traits>
 
 #include "process-utils.h"
+#include "Basics/system-functions.h"
 
 #if defined(TRI_HAVE_MACOS_MEM_STATS)
 #include <sys/sysctl.h>
@@ -1029,16 +1030,41 @@ ExternalProcessStatus TRI_CheckExternalProcess(ExternalId pid, bool wait, uint32
 
   if (external->_status == TRI_EXT_RUNNING || external->_status == TRI_EXT_STOPPED) {
 #ifndef _WIN32
-    int opts;
-    int loc = 0;
+    if (timeout > 0) {
+      // if we use a timeout, it means we cannot use blocking
+      wait = false;
+    }
 
+    int opts;
     if (wait) {
       opts = WUNTRACED;
     } else {
       opts = WNOHANG | WUNTRACED;
     }
 
-    TRI_pid_t res = waitpid(external->_pid, &loc, opts);
+    int loc = 0;
+    TRI_pid_t res = 0;
+    if (timeout) {
+      TRI_ASSERT((opts & WNOHANG) != 0);
+      double endTime = 0.0; 
+      while (true) {
+        res = waitpid(external->_pid, &loc, opts);
+        if (res != 0) {
+          break;
+        }
+        double now = TRI_microtime();
+        if (endTime <= 0.000001) {
+          // set endtime only once
+          endTime = now + timeout / 1000.0;
+        } else if (now >= endTime) {
+          // timeout
+          break;
+        }
+        std::this_thread::sleep_for(std::chrono::milliseconds(20));
+      }
+    } else {
+      res = waitpid(external->_pid, &loc, opts);
+    }
 
     if (res == 0) {
       if (wait) {
diff --git a/lib/V8/v8-utils.cpp b/lib/V8/v8-utils.cpp
@@ -4422,7 +4422,7 @@ static void JS_StatusExternal(v8::FunctionCallbackInfo<v8::Value> const& args) {
 /// @brief executes a external program
 ////////////////////////////////////////////////////////////////////////////////
 
-static void JS_ExecuteAndWaitExternal(v8::FunctionCallbackInfo<v8::Value> const& args) {
+static void JS_ExecuteExternalAndWait(v8::FunctionCallbackInfo<v8::Value> const& args) {
   TRI_V8_TRY_CATCH_BEGIN(isolate);
   v8::HandleScope scope(isolate);
 
@@ -5563,7 +5563,7 @@ void TRI_InitV8Utils(v8::Isolate* isolate, v8::Handle<v8::Context> context,
                                JS_ExecuteExternal);
   TRI_AddGlobalFunctionVocbase(
       isolate, TRI_V8_ASCII_STRING(isolate, "SYS_EXECUTE_EXTERNAL_AND_WAIT"),
-      JS_ExecuteAndWaitExternal);
+      JS_ExecuteExternalAndWait);
   TRI_AddGlobalFunctionVocbase(
       isolate, TRI_V8_ASCII_STRING(isolate, "SYS_GEN_RANDOM_ALPHA_NUMBERS"), JS_RandomAlphaNum);
   TRI_AddGlobalFunctionVocbase(isolate,
