am 53630c0e: Merge "Cache the most-recently used timezone for mktime_tz and localtime_tz."

* commit '53630c0e5bb6f845ba633e8dedc08b827f7b5d0c':
  Cache the most-recently used timezone for mktime_tz and localtime_tz.

libc/tzcode/localtime.c

@@ -404,10 +404,7 @@ static int toint(unsigned char *s) {
 }
 
 static int
-tzload(name, sp, doextend)
-register const char *       name;
-register struct state * const   sp;
-register const int      doextend;
+tzload(const char* name, struct state* const sp, const int doextend)
 {
     register const char *       p;
     register int            i;
@@ -2068,32 +2065,55 @@ struct tm * const   tmp;
 }
 
 // BEGIN android-added
-time_t
-mktime_tz(tmp, tz)
-struct tm * const tmp;
-char const * tz;
-{
+
+// Caches the most recent timezone (http://b/8270865).
+static int __bionic_tzload_cached(const char* name, struct state* const sp, const int doextend) {
+  _tzLock();
+
+  // Our single-item cache.
+  static char* gCachedTimeZoneName;
+  static struct state gCachedTimeZone;
+
+  // Do we already have this timezone cached?
+  if (gCachedTimeZoneName != NULL && strcmp(name, gCachedTimeZoneName) == 0) {
+    *sp = gCachedTimeZone;
+    _tzUnlock();
+    return 0;
+  }
+
+  // Can we load it?
+  int rc = tzload(name, sp, doextend);
+  if (rc == 0) {
+    // Update the cache.
+    free(gCachedTimeZoneName);
+    gCachedTimeZoneName = strdup(name);
+    gCachedTimeZone = *sp;
+  }
+
+  _tzUnlock();
+  return rc;
+}
+
+// Non-standard API: mktime(3) but with an explicit timezone parameter.
+time_t mktime_tz(struct tm* const tmp, const char* tz) {
   struct state st;
-    if (tzload(tz, &st, TRUE) != 0) {
+  if (__bionic_tzload_cached(tz, &st, TRUE) != 0) {
     // TODO: not sure what's best here, but for now, we fall back to gmt.
     gmtload(&st);
   }
   return time1(tmp, localsub, 0L, &st);
 }
 
-void
-localtime_tz(timep, tmp, tz)
-const time_t * const timep;
-struct tm * tmp;
-const char* tz;
-{
+// Non-standard API: localtime(3) but with an explicit timezone parameter.
+void localtime_tz(const time_t* const timep, struct tm* tmp, const char* tz) {
   struct state st;
-    if (tzload(tz, &st, TRUE) != 0) {
+  if (__bionic_tzload_cached(tz, &st, TRUE) != 0) {
     // TODO: not sure what's best here, but for now, we fall back to gmt.
     gmtload(&st);
   }
   localsub(timep, 0L, tmp, &st);
 }
+
 // END android-added
 
 #ifdef STD_INSPIRED

tests/Android.mk

@@ -32,6 +32,7 @@ benchmark_src_files = \
     benchmark_main.cpp \
     math_benchmark.cpp \
     string_benchmark.cpp \
+    time_benchmark.cpp \
 
 # Build benchmarks for the device (with bionic's .so). Run with:
 #   adb shell bionic-benchmarks

tests/time_benchmark.cpp

@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "benchmark.h"
+
+#include <time.h>
+
+#if defined(__BIONIC__)
+
+// Used by the horrible android.text.format.Time class, which is used by Calendar. http://b/8270865.
+extern "C" void localtime_tz(const time_t* const timep, struct tm* tmp, const char* tz);
+
+static void BM_time_localtime_tz(int iters) {
+  StartBenchmarkTiming();
+
+  time_t now(time(NULL));
+  tm broken_down_time;
+  for (int i = 0; i < iters; ++i) {
+    localtime_tz(&now, &broken_down_time, "Europe/Berlin");
+  }
+
+  StopBenchmarkTiming();
+}
+BENCHMARK(BM_time_localtime_tz);
+#endif