From 442aa1f4696d24a605790b8ad4317696758ee8de Mon Sep 17 00:00:00 2001
From: Brian White <mscdex@mscdex.net>
Date: Fri, 24 Feb 2012 11:56:15 -0500
Subject: [PATCH] win: use performance counter instead of GetTickCount for
 uptime

---
 src/win/util.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 64 insertions(+), 2 deletions(-)

diff --git a/src/win/util.c b/src/win/util.c
index 9f731ecf..68b14fb0 100644
--- a/src/win/util.c
+++ b/src/win/util.c
@@ -385,8 +385,70 @@ uv_err_t uv_resident_set_memory(size_t* rss) {
 
 
 uv_err_t uv_uptime(double* uptime) {
-  *uptime = (double)GetTickCount()/1000.0;
-  return uv_ok_;
+  uv_err_t err;
+  PERF_DATA_BLOCK *dataBlock = NULL;
+  PERF_OBJECT_TYPE *objType;
+  PERF_COUNTER_DEFINITION *counterDef;
+  PERF_COUNTER_DEFINITION *counterDefUptime = NULL;
+  DWORD dataSize = 4096;
+  DWORD getSize;
+  LONG lError = ERROR_MORE_DATA;
+  uint64_t upsec;
+  unsigned int i;
+  BYTE *counterData;
+
+  *uptime = 0;
+  
+  while (lError == ERROR_MORE_DATA) {
+    if (dataBlock) {
+      free(dataBlock);
+    }
+    dataBlock = (PERF_DATA_BLOCK*)malloc(dataSize);
+    if (!dataBlock) {
+      uv_fatal_error(ERROR_OUTOFMEMORY, "malloc");
+    }
+    getSize = dataSize;
+
+    lError = RegQueryValueExW(HKEY_PERFORMANCE_DATA, "2", NULL, NULL,
+                             (BYTE*)dataBlock, &getSize);
+    if (lError != ERROR_SUCCESS && getSize > 0) {
+      if (wcsncmp(dataBlock->Signature, "PERF", 4) == 0) {
+        break;
+      }
+    } else if (lError != ERROR_SUCCESS && lError != ERROR_MORE_DATA) {
+      err = uv__new_sys_error(GetLastError());
+      goto done;
+    }
+
+    dataSize += 1024;
+  }
+
+  RegCloseKey(HKEY_PERFORMANCE_DATA);
+
+  objType = (PERF_OBJECT_TYPE*)((BYTE*)dataBlock + dataBlock->HeaderLength);
+  counterDef = (PERF_COUNTER_DEFINITION*)((BYTE*)objType + objType->HeaderLength);
+
+  for (i = 0; i < objType->NumCounters; ++i) {
+    if (counterDef->CounterNameTitleIndex == 674) {
+      counterDefUptime = counterDef;
+      break;
+    }
+    counterDef = (PERF_COUNTER_DEFINITION*)((BYTE*)counterDef + counterDef->ByteLength);
+  }
+
+  counterData = (BYTE*)objType + objType->DefinitionLength;
+  counterData += counterDefUptime->CounterOffset;
+
+  upsec = *((uint64_t*)counterData);
+  *uptime = ((objType->PerfTime.QuadPart - upsec) / objType->PerfFreq.QuadPart);
+  err = uv_ok_;
+
+done:
+  if (dataBlock) {
+    free(dataBlock);
+  }
+
+  return err;
 }