Use own private mutex for guarding pool in BreakerPool

To be independent from gMinikinLock, introduce own private mutex for
guarding mPool in ICULineBreakerPoolImpl.

Here is a raw performance score:

StaticLayout creation time:
 MeasuredText Balanced Hyphenation  :    704,994 ->    702,566: (-0.3%)
 MeasuredText Balanced NoHyphenation:    539,847 ->    545,703: (+1.1%)
 MeasuredText Greedy Hyphenation    :    494,681 ->    494,209: (-0.1%)
 MeasuredText Greedy NoHyphenation  :    488,553 ->    492,238: (+0.8%)
 RandomText Balanced Hyphenation    : 18,148,346 -> 18,186,174: (+0.2%)
 RandomText Balanced NoHyphenation  :  7,631,448 ->  7,650,471: (+0.2%)
 RandomText Greedy Hyphenation      :  7,515,126 ->  7,580,007: (+0.9%)
 RandomText Greedy NoHyphenation    :  7,575,344 ->  7,594,000: (+0.2%)

MeasuredText creation time:
 NoStyled Hyphenation               : 18,004,921 -> 18,084,752: (+0.4%)
 NoStyled Hyphenation WidthOnly     : 17,459,350 -> 17,583,465: (+0.7%)
 NoStyled NoHyphenation             :  7,601,492 ->  7,617,908: (+0.2%)
 NoStyled NoHyphenation WidthOnly   :  7,122,189 ->  7,151,384: (+0.4%)
 Styled Hyphenation                 : 14,961,242 -> 14,842,647: (-0.8%)
 Styled Hyphenation WidthOnly       : 14,067,121 -> 13,925,084: (-1.0%)
 Styled NoHyphenation               : 14,470,800 -> 14,378,989: (-0.6%)
 Styled NoHyphenation WidthOnly     : 13,568,743 -> 13,587,057: (+0.1%)

StaticLayout draw time:
 MeasuredText NoStyled              :    658,118 ->    667,373: (+1.4%)
 MeasuredText NoStyled WithoutCache :    654,450 ->    651,152: (-0.5%)
 MeasuredText Styled                :    897,991 ->    856,718: (-4.6%)
 MeasuredText Styled WithoutCache   :    911,318 ->    909,806: (-0.2%)
 RandomText NoStyled                :    574,551 ->    585,543: (+1.9%)
 RandomText NoStyled WithoutCache   :  6,918,073 ->  6,904,898: (-0.2%)
 RandomText Styled                  :  2,978,776 ->  2,964,139: (-0.5%)
 RandomText Styled WithoutCache     :  3,402,067 ->  3,411,934: (+0.3%)

Bug: 37567215
Test: minikin tests
Change-Id: I062b44ea87f3b0abaf859c738605b67d2ba0fbf2

2 files changed, 5 insertions, 3 deletions

diff --git a/libs/minikin/WordBreaker.cpp b/libs/minikin/WordBreaker.cpp
index 12d64f8..dae5cab 100644
--- a/libs/minikin/WordBreaker.cpp
+++ b/libs/minikin/WordBreaker.cpp
@@ -43,7 +43,7 @@ static icu::BreakIterator* createNewIterator(const Locale& locale) {
 
 ICULineBreakerPool::Slot ICULineBreakerPoolImpl::acquire(const Locale& locale) {
     const uint64_t id = locale.getIdentifier();
-    android::AutoMutex _l(gMinikinLock);
+    std::lock_guard<std::mutex> lock(mMutex);
     for (auto i = mPool.begin(); i != mPool.end(); i++) {
         if (i->localeId == id) {
             Slot slot = std::move(*i);
@@ -60,7 +60,7 @@ void ICULineBreakerPoolImpl::release(ICULineBreakerPool::Slot&& slot) {
     if (slot.breaker.get() == nullptr) {
         return;  // Already released slot. Do nothing.
     }
-    android::AutoMutex _l(gMinikinLock);
+    std::lock_guard<std::mutex> lock(mMutex);
     if (mPool.size() >= MAX_POOL_SIZE) {
         // Pool is full. Move to local variable, so that the given slot will be released when the
         // variable leaves the scope.
diff --git a/libs/minikin/WordBreaker.h b/libs/minikin/WordBreaker.h
index 84d1d62..ca4648e 100644
--- a/libs/minikin/WordBreaker.h
+++ b/libs/minikin/WordBreaker.h
@@ -24,6 +24,7 @@
 #define MINIKIN_WORD_BREAKER_H
 
 #include <list>
+#include <mutex>
 
 #include <unicode/brkiter.h>
 
@@ -76,7 +77,8 @@ protected:
     size_t getPoolSize() const { return mPool.size(); }
 
 private:
-    std::list<Slot> mPool;  // Guarded by gMinikinLock
+    std::list<Slot> mPool;  // Guarded by mMutex
+    std::mutex mMutex;
 };
 
 class WordBreaker {