Add function to compute proportional set size for OS_WIN

base/process/process_metrics_win.cc

Index: base/process/process_metrics_win.cc
diff --git a/base/process/process_metrics_win.cc b/base/process/process_metrics_win.cc
index 5b2777bb364bfa1c53679432fd511acfb8dbd4a4..d8261bf582e03305c95b63f9ebf36dc95f72288f 100644
--- a/base/process/process_metrics_win.cc
+++ b/base/process/process_metrics_win.cc
@@ -171,20 +171,15 @@ class WorkingSetInformationBuffer {
 
 }  // namespace
 
-bool ProcessMetrics::GetWorkingSetKBytes(WorkingSetKBytes* ws_usage) const {
-  size_t ws_private = 0;
-  size_t ws_shareable = 0;
-  size_t ws_shared = 0;
-
-  DCHECK(ws_usage);
-  memset(ws_usage, 0, sizeof(*ws_usage));
-
-  DWORD number_of_entries = 4096;  // Just a guess.
-  WorkingSetInformationBuffer buffer;
+// This is a helper function to get number of page entries for a process.
+bool GetPageEntriesNum(WorkingSetInformationBuffer& buffer,

[brucedawson, 2016/12/05 19:22:02]

The name of this function is misleading. It sounds like it will just get the
number of page entries, but it actually gets the page entries (getting the
number of them is part of this). If you remove 'Num' from the name then I think
it is more accurate.

Also, I believe the style guide prohibits non-const references. So, you need to
use a pointer to buffer instead.

[chengx, 2016/12/06 02:51:38]

Done.

+                       const ProcessHandle& process_,
+                       DWORD* number_of_entries) {
   int retries = 5;
+
   for (;;) {
     DWORD buffer_size = sizeof(PSAPI_WORKING_SET_INFORMATION) +
-                        (number_of_entries * sizeof(PSAPI_WORKING_SET_BLOCK));
+                        (*number_of_entries * sizeof(PSAPI_WORKING_SET_BLOCK));
 
     if (!buffer.Reserve(buffer_size))
       return false;
@@ -196,14 +191,14 @@ bool ProcessMetrics::GetWorkingSetKBytes(WorkingSetKBytes* ws_usage) const {
     if (GetLastError() != ERROR_BAD_LENGTH)
       return false;
 
-    number_of_entries = static_cast<DWORD>(buffer->NumberOfEntries);
+    *number_of_entries = static_cast<DWORD>(buffer->NumberOfEntries);
 
     // Maybe some entries are being added right now. Increase the buffer to
     // take that into account. Increasing by 10% should generally be enough,
     // especially considering the potentially low memory condition during the
     // call (when called from OomMemoryDetails) and the potentially high
     // number of entries (300K was observed in crash dumps).
-    number_of_entries = static_cast<DWORD>(number_of_entries * 1.1);
+    *number_of_entries = static_cast<DWORD>(*number_of_entries * 1.1);
 
     if (--retries == 0) {
       // If we're looping, eventually fail.
@@ -214,8 +209,25 @@ bool ProcessMetrics::GetWorkingSetKBytes(WorkingSetKBytes* ws_usage) const {
   // On windows 2000 the function returns 1 even when the buffer is too small.
   // The number of entries that we are going to parse is the minimum between the
   // size we allocated and the real number of entries.
-  number_of_entries =
-      std::min(number_of_entries, static_cast<DWORD>(buffer->NumberOfEntries));
+  *number_of_entries =
+      std::min(*number_of_entries, static_cast<DWORD>(buffer->NumberOfEntries));
+
+  return true;
+}
+
+bool ProcessMetrics::GetWorkingSetKBytes(WorkingSetKBytes* ws_usage) const {
+  size_t ws_private = 0;
+  size_t ws_shareable = 0;
+  size_t ws_shared = 0;
+
+  DCHECK(ws_usage);
+  memset(ws_usage, 0, sizeof(*ws_usage));
+
+  DWORD number_of_entries = 4096;  // Just a guess.

[brucedawson, 2016/12/05 19:22:02]

Probably no need to put this guess here. Instead have GetPageEntriesNum do the
initial guess.

Maybe put number_of_entries as par of WorkingSetInformationBuffer - better
encapsulation.

[chengx, 2016/12/06 02:51:38]

Done.

+  WorkingSetInformationBuffer buffer;
+  if (!GetPageEntriesNum(buffer, process_, &number_of_entries))
+    return false;
+
   for (unsigned int i = 0; i < number_of_entries; i++) {
     if (buffer->WorkingSetInfo[i].Shared) {
       ws_shareable++;
@@ -229,6 +241,28 @@ bool ProcessMetrics::GetWorkingSetKBytes(WorkingSetKBytes* ws_usage) const {
   ws_usage->priv = ws_private * PAGESIZE_KB;
   ws_usage->shareable = ws_shareable * PAGESIZE_KB;
   ws_usage->shared = ws_shared * PAGESIZE_KB;
+
+  return true;
+}
+
+// This function calculates the proportional set size for a process.
+bool ProcessMetrics::GetProportionalSetSizeBytes(uint64_t* pss_bytes) const {
+  double ws_pss = 0.0f;
+
+  DWORD number_of_entries = 4096;  // Just a guess.
+  WorkingSetInformationBuffer buffer;
+  if (!GetPageEntriesNum(buffer, process_, &number_of_entries))
+    return false;
+
+  for (unsigned int i = 0; i < number_of_entries; i++) {
+    if (buffer->WorkingSetInfo[i].Shared &&
+        buffer->WorkingSetInfo[i].ShareCount > 0)
+      ws_pss += 1.0f / buffer->WorkingSetInfo[i].ShareCount;
+    else
+      ws_pss += 1.0f;
+  }
+
+  *pss_bytes = static_cast<uint64_t>(ws_pss);
   return true;
 }