From 539690a351d8c325707368729aafa2b4fa134d4c Mon Sep 17 00:00:00 2001
From: Vladimir Marko <vmarko@google.com>
Date: Thu, 5 Jun 2014 18:36:42 +0100
Subject: Avoid a memory allocation in OatFile::GetOatDexFile().

Use StringPiece instead of std::string as the map key.

Change-Id: I05516d273de617a7d714e39ce6c4236cec6a09f7
---
 runtime/oat_file.cc | 13 ++++++++-----
 runtime/oat_file.h  | 15 +++++++++------
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/runtime/oat_file.cc b/runtime/oat_file.cc
index 74dfe91..6c44aa9 100644
--- a/runtime/oat_file.cc
+++ b/runtime/oat_file.cc
@@ -292,11 +292,14 @@ bool OatFile::Setup(std::string* error_msg) {
       return false;
     }
 
-    oat_dex_files_.Put(dex_file_location, new OatDexFile(this,
-                                                         dex_file_location,
-                                                         dex_file_checksum,
-                                                         dex_file_pointer,
-                                                         methods_offsets_pointer));
+    OatDexFile* oat_dex_file = new OatDexFile(this,
+                                              dex_file_location,
+                                              dex_file_checksum,
+                                              dex_file_pointer,
+                                              methods_offsets_pointer);
+    // Use a StringPiece backed by the oat_dex_file's internal std::string as the key.
+    StringPiece key(oat_dex_file->GetDexFileLocation());
+    oat_dex_files_.Put(key, oat_dex_file);
   }
   return true;
 }
diff --git a/runtime/oat_file.h b/runtime/oat_file.h
index d703731..eae0418 100644
--- a/runtime/oat_file.h
+++ b/runtime/oat_file.h
@@ -20,6 +20,7 @@
 #include <string>
 #include <vector>
 
+#include "base/stringpiece.h"
 #include "dex_file.h"
 #include "invoke_type.h"
 #include "mem_map.h"
@@ -206,11 +207,11 @@ class OatFile {
                const byte* dex_file_pointer,
                const uint32_t* oat_class_offsets_pointer);
 
-    const OatFile* oat_file_;
-    std::string dex_file_location_;
-    uint32_t dex_file_location_checksum_;
-    const byte* dex_file_pointer_;
-    const uint32_t* oat_class_offsets_pointer_;
+    const OatFile* const oat_file_;
+    const std::string dex_file_location_;
+    const uint32_t dex_file_location_checksum_;
+    const byte* const dex_file_pointer_;
+    const uint32_t* const oat_class_offsets_pointer_;
 
     friend class OatFile;
     DISALLOW_COPY_AND_ASSIGN(OatDexFile);
@@ -270,7 +271,9 @@ class OatFile {
   // dlopen handle during runtime.
   void* dlopen_handle_;
 
-  typedef SafeMap<std::string, const OatDexFile*> Table;
+  // NOTE: We use a StringPiece as the key type to avoid a memory allocation on every lookup
+  // with a const char* key.
+  typedef SafeMap<StringPiece, const OatDexFile*> Table;
   Table oat_dex_files_;
 
   friend class OatClass;
-- 
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