From 13fc91124c4b59f366c7983aba78e0741f664da8 Mon Sep 17 00:00:00 2001
From: Dwight <dwight@10gen.com>
Date: Mon, 17 May 2010 18:06:53 -0400
Subject: [PATCH] task

---
 db/db.cpp                 |  1 +
 util/concurrency/task.cpp | 72 ++++++++++++++++++++++++++++++++++++---
 util/concurrency/task.h   | 26 ++++++++++----
 3 files changed, 88 insertions(+), 11 deletions(-)

diff --git a/db/db.cpp b/db/db.cpp
index 5f77a3c1db4..8b2238e7270 100644
--- a/db/db.cpp
+++ b/db/db.cpp
@@ -43,6 +43,7 @@
 #include "module.h"
 #include "cmdline.h"
 #include "stats/snapshots.h"
+#include "../util/concurrency/task.h"
 
 namespace mongo {
 
diff --git a/util/concurrency/task.cpp b/util/concurrency/task.cpp
index bd549eab29d..3347043d024 100644
--- a/util/concurrency/task.cpp
+++ b/util/concurrency/task.cpp
@@ -18,17 +18,79 @@
 
 #include "pch.h"
 #include "task.h"
+//#include "../goodies.h"
 
 namespace mongo { 
 
     namespace task { 
-    
-        Task::~Task() { }
 
-        void Task::run() { }
+/*
+#define MS_VC_EXCEPTION 0x406D1388
+
+#pragma pack(push,8)
+typedef struct tagTHREADNAME_INFO
+{
+   DWORD dwType; // Must be 0x1000.
+   LPCSTR szName; // Pointer to name (in user addr space).
+   DWORD dwThreadID; // Thread ID (-1=caller thread).
+   DWORD dwFlags; // Reserved for future use, must be zero.
+} THREADNAME_INFO;
+#pragma pack(pop)
+
+void SetThreadName( DWORD dwThreadID, char* threadName)
+{
+   Sleep(10);
+   THREADNAME_INFO info;
+   info.dwType = 0x1000;
+   info.szName = threadName;
+   info.dwThreadID = dwThreadID;
+   info.dwFlags = 0;
+
+   __try
+   {
+      RaiseException( MS_VC_EXCEPTION, 0, sizeof(info)/sizeof(ULONG_PTR), (ULONG_PTR*)&info );
+   }
+   __except(EXCEPTION_EXECUTE_HANDLER)
+   {
+   }
+}
+*/
 
-        void fork(const shared_ptr<Task>& t) { 
-            cout << "not yet implemented" << endl;
+        Task::Task() { 
+            n = 0;
+            repeat = 0;
+        }
+
+        void Task::halt() { repeat = 0; }
+
+        void Task::run() { 
+            //SetThreadName(-1, "A Task");
+            assert( n == 0 );
+            while( 1 ) {
+                n++;
+                try { 
+                    doWork();
+                } 
+                catch(...) { }
+                if( repeat == 0 )
+                    break;
+                sleepmillis(repeat);
+            }
+            me.reset();
+        }
+
+        void Task::begin(shared_ptr<Task> t) {
+            me = t;
+            go();
+        }
+
+        void fork(shared_ptr<Task> t) { 
+            t->begin(t);
+        }
+
+        void repeat(shared_ptr<Task> t, unsigned millis) { 
+            t->repeat = millis;
+            t->begin(t);
         }
     
     }
diff --git a/util/concurrency/task.h b/util/concurrency/task.h
index 02a7968d727..c91df65277e 100644
--- a/util/concurrency/task.h
+++ b/util/concurrency/task.h
@@ -24,22 +24,36 @@ namespace mongo {
 
     namespace task { 
 
-        class Task : protected BackgroundJob { 
-            virtual void run();
+        class Task : private BackgroundJob {
         protected:
-            virtual void go() = 0;
+            virtual void doWork() = 0;
         public:
-            virtual ~Task();
+            Task();
+
+            /** for a repeating task, stop after current invocation ends. */
+            void halt();
+
+        private:
+            shared_ptr<Task> me;
+            unsigned n, repeat;
+            friend void fork(shared_ptr<Task> t);
+            friend void repeat(shared_ptr<Task> t, unsigned millis);
+            virtual void run();
+            void begin(shared_ptr<Task>);
         };
 
-        void fork(const shared_ptr<Task>& t);
+        /* run once */
+        void fork(shared_ptr<Task> t);
+
+        /* run doWork() over and over, with a pause between runs of millis */
+        void repeat(shared_ptr<Task> t, unsigned millis);
 
         /*** Example ***
         inline void sample() { 
             class Sample : public Task { 
             public:
                 int result;
-                virtual void go() { result = 1234; }
+                virtual void doWork() { result = 1234; }
                 Sample() : result(0) { }
             };
             shared_ptr<Sample> q( new Sample() );