From 7afa6f3a5c5a13fda9e96b65dee2c08071af0c05 Mon Sep 17 00:00:00 2001
From: "siggi@chromium.org"
 <siggi@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98>
Date: Thu, 31 May 2012 12:54:52 +0000
Subject: Signal thread names in instrumented binaries, even when a debugger is
 not attached.

Cache the determiniation whether a binary is instrumented or not, as it'll never change for a given binary.

R=jar@google.com
BUG=None
TEST=None


Review URL: https://chromiumcodereview.appspot.com/10454076

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@139777 0039d316-1c4b-4281-b951-d872f2087c98
---
 base/debug/profiler.cc                | 37 +++++++++++++++++++++++++----------
 base/threading/platform_thread_win.cc |  5 ++++-
 2 files changed, 31 insertions(+), 11 deletions(-)

(limited to 'base')

diff --git a/base/debug/profiler.cc b/base/debug/profiler.cc
index e1f2514..de79124 100644
--- a/base/debug/profiler.cc
+++ b/base/debug/profiler.cc
@@ -88,17 +88,34 @@ ReturnAddressLocationResolver GetProfilerReturnAddrResolutionFunc() {
 extern "C" IMAGE_DOS_HEADER __ImageBase;
 
 bool IsBinaryInstrumented() {
-  HMODULE this_module = reinterpret_cast<HMODULE>(&__ImageBase);
-  base::win::PEImage image(this_module);
-
-  // This should be self-evident, soon as we're executing.
-  DCHECK(image.VerifyMagic());
+  enum InstrumentationCheckState {
+    UNINITIALIZED,
+    INSTRUMENTED_IMAGE,
+    NON_INSTRUMENTED_IMAGE,
+  };
+
+  static InstrumentationCheckState state = UNINITIALIZED;
+
+  if (state == UNINITIALIZED) {
+    HMODULE this_module = reinterpret_cast<HMODULE>(&__ImageBase);
+    base::win::PEImage image(this_module);
+
+    // Check to be sure our image is structured as we'd expect.
+    DCHECK(image.VerifyMagic());
+
+    // Syzygy-instrumented binaries contain a PE image section named ".thunks",
+    // and all Syzygy-modified binaries contain the ".syzygy" image section.
+    // This is a very fast check, as it only looks at the image header.
+    if ((image.GetImageSectionHeaderByName(".thunks") != NULL) &&
+        (image.GetImageSectionHeaderByName(".syzygy") != NULL)) {
+      state = INSTRUMENTED_IMAGE;
+    } else {
+      state = NON_INSTRUMENTED_IMAGE;
+    }
+  }
+  DCHECK(state != UNINITIALIZED);
 
-  // Syzygy-instrumented binaries contain a PE image section named ".thunks",
-  // and all Syzygy-modified binaries contain the ".syzygy" image section.
-  // This is a very fast check, as it only looks at the image header.
-  return (image.GetImageSectionHeaderByName(".thunks") != NULL) &&
-      (image.GetImageSectionHeaderByName(".syzygy") != NULL);
+  return state == INSTRUMENTED_IMAGE;
 }
 
 // Callback function to PEImage::EnumImportChunks.
diff --git a/base/threading/platform_thread_win.cc b/base/threading/platform_thread_win.cc
index bd4282f..4dc839b 100644
--- a/base/threading/platform_thread_win.cc
+++ b/base/threading/platform_thread_win.cc
@@ -5,6 +5,7 @@
 #include "base/threading/platform_thread.h"
 
 #include "base/debug/alias.h"
+#include "base/debug/profiler.h"
 #include "base/logging.h"
 #include "base/threading/thread_local.h"
 #include "base/threading/thread_restrictions.h"
@@ -133,7 +134,9 @@ void PlatformThread::SetName(const char* name) {
 
   // The debugger needs to be around to catch the name in the exception.  If
   // there isn't a debugger, we are just needlessly throwing an exception.
-  if (!::IsDebuggerPresent())
+  // If this image file is instrumented, we raise the exception anyway
+  // to provide the profiler with human-readable thread names.
+  if (!::IsDebuggerPresent() && !base::debug::IsBinaryInstrumented())
     return;
 
   SetNameInternal(CurrentId(), name);
-- 
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