Bug 1525086 - Part 4 - Cache the result of nsMacUtilsImpl::GetAppPath r=Alex_Gaynor

Cache the result of nsMacUtilsImpl::GetAppPath() to avoid doing I/O on repeated calls.

Differential Revision: https://phabricator.services.mozilla.com/D22410

--HG--
extra : moz-landing-system : lando

xpcom/base/nsMacUtilsImpl.cpp

@@ -7,6 +7,7 @@
 #include "nsMacUtilsImpl.h"
 
 #include "base/command_line.h"
+#include "mozilla/ClearOnShutdown.h"
 #include "nsDirectoryServiceDefs.h"
 #include "nsCOMPtr.h"
 #include "nsIFile.h"
@@ -18,6 +19,13 @@
 
 NS_IMPL_ISUPPORTS(nsMacUtilsImpl, nsIMacUtils)
 
+using mozilla::StaticMutexAutoLock;
+
+#if defined(MOZ_SANDBOX)
+StaticAutoPtr<nsCString> nsMacUtilsImpl::sCachedAppPath;
+StaticMutex nsMacUtilsImpl::sCachedAppPathMutex;
+#endif
+
 nsresult nsMacUtilsImpl::GetArchString(nsAString& aArchString) {
   if (!mBinaryArchs.IsEmpty()) {
     aArchString.Assign(mBinaryArchs);
@@ -134,6 +142,12 @@ nsMacUtilsImpl::GetIsTranslated(bool* aIsTranslated) {
 // executable. We don't rely on the actual .app extension to allow for the
 // bundle being renamed.
 bool nsMacUtilsImpl::GetAppPath(nsCString& aAppPath) {
+  StaticMutexAutoLock lock(sCachedAppPathMutex);
+  if (sCachedAppPath) {
+    aAppPath.Assign(*sCachedAppPath);
+    return true;
+  }
+
   nsAutoCString appPath;
   nsAutoCString appBinaryPath(
       (CommandLine::ForCurrentProcess()->argv()[0]).c_str());
@@ -179,6 +193,11 @@ bool nsMacUtilsImpl::GetAppPath(nsCString& aAppPath) {
   }
   app->GetNativePath(aAppPath);
 
+  if (!sCachedAppPath) {
+    sCachedAppPath = new nsCString(aAppPath);
+    ClearOnShutdown(&sCachedAppPath);
+  }
+
   return true;
 }
 

xpcom/base/nsMacUtilsImpl.h

@@ -10,6 +10,11 @@
 #include "nsIMacUtils.h"
 #include "nsString.h"
 #include "mozilla/Attributes.h"
+#include "mozilla/StaticMutex.h"
+#include "mozilla/StaticPtr.h"
+
+using mozilla::StaticAutoPtr;
+using mozilla::StaticMutex;
 
 class nsMacUtilsImpl final : public nsIMacUtils {
  public:
@@ -34,6 +39,13 @@ class nsMacUtilsImpl final : public nsIMacUtils {
   // A string containing a "-" delimited list of architectures
   // in our binary.
   nsString mBinaryArchs;
+
+#if defined(MOZ_SANDBOX)
+  // Cache the appDir returned from GetAppPath to avoid doing I/O
+  static StaticAutoPtr<nsCString> sCachedAppPath;
+  // For thread safe setting/checking of sCachedAppPath
+  static StaticMutex sCachedAppPathMutex;
+#endif
 };
 
 // Global singleton service