From 749f51d769e79683b8bcfe0bb20d8261dd41d2a0 Mon Sep 17 00:00:00 2001
From: George Rhoten <grhoten@users.noreply.github.com>
Date: Fri, 9 May 2003 21:33:17 +0000
Subject: [PATCH] ICU-2787 A lock doesn't need to happen when it's an
 algorithmic converter.

X-SVN-Rev: 11874
---
 icu4c/source/common/ucnv.c     | 18 ++++++++++++++++--
 icu4c/source/common/ucnv_bld.c |  9 +++++++--
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/icu4c/source/common/ucnv.c b/icu4c/source/common/ucnv.c
index 21bb020f0d2..be7c686a478 100644
--- a/icu4c/source/common/ucnv.c
+++ b/icu4c/source/common/ucnv.c
@@ -289,7 +289,14 @@ ucnv_safeClone(const UConverter* cnv, void *stackBuffer, int32_t *pBufferSize, U
     }
 
     /* increment refcount of shared data if needed */
-    ucnv_incrementRefCount(cnv->sharedData);
+    /*
+    Checking whether it's an algorithic converter is okay
+    in multithreaded applications because the value never changes.
+    Don't check referenceCounter for any other value.
+    */
+    if (cnv->sharedData->referenceCounter != ~0) {
+        ucnv_incrementRefCount(cnv->sharedData);
+    }
 
     if(localConverter==NULL || U_FAILURE(*status)) {
         return NULL;
@@ -390,7 +397,14 @@ ucnv_close (UConverter * converter)
     }
 #endif
 
-    ucnv_unloadSharedDataIfReady(converter->sharedData);
+    /*
+    Checking whether it's an algorithic converter is okay
+    in multithreaded applications because the value never changes.
+    Don't check referenceCounter for any other value.
+    */
+    if (converter->sharedData->referenceCounter != ~0) {
+        ucnv_unloadSharedDataIfReady(converter->sharedData);
+    }
 
     if(!converter->isCopyLocal){
         UCNV_DEBUG_LOG("close:free", "", converter);
diff --git a/icu4c/source/common/ucnv_bld.c b/icu4c/source/common/ucnv_bld.c
index 3238dd5709a..16e87969f3b 100644
--- a/icu4c/source/common/ucnv_bld.c
+++ b/icu4c/source/common/ucnv_bld.c
@@ -656,11 +656,16 @@ ucnv_createConverter(UConverter *myUConverter, const char *converterName, UError
 
     if (U_FAILURE(*err))
     {
-        umtx_lock(&cnvCacheMutex);
+        /*
+        Checking whether it's an algorithic converter is okay
+        in multithreaded applications because the value never changes.
+        Don't check referenceCounter for any other value.
+        */
         if (mySharedConverterData->referenceCounter != ~0) {
+            umtx_lock(&cnvCacheMutex);
             --mySharedConverterData->referenceCounter;
+            umtx_unlock(&cnvCacheMutex);
         }
-        umtx_unlock(&cnvCacheMutex);
         return NULL;
     }