ICU-2849 document that u_setDataDirectory() is not thread-safe

X-SVN-Rev: 12182

icu4c/source/common/unicode/putil.h

@@ -254,9 +254,8 @@ U_CAPI int32_t  U_EXPORT2 uprv_getUTCtime(void);
  * The data directory is determined as follows:
  *    If u_setDataDirectory() has been called, that is it, otherwise
  *    if the ICU_DATA environment variable is set, use that, otherwise
- *    On Windows, if the SOFTWARE\ICU\Unicode\Data registry entry exists, use that
- *           (use of the registry in this way is not recommended.)  otherwise
- *    If a data directory was specifed at ICU build time, use that
+ *    If a data directory was specifed at ICU build time
+ *      (#define ICU_DATA_DIR "path"), use that,
  *    otherwise no data directory is available.
  *
  * @return the data directory, or an empty string ("") if no data directory has
@@ -275,8 +274,14 @@ U_CAPI const char* U_EXPORT2 u_getDataDirectory(void);
  *   does not need to be set.
  *
  * This function should be called at most once in a process, before the
- * first ICU operation that will require the loading of an ICU data file.
- * @param disrectory The directory to be set.
+ * first ICU operation (e.g., u_init()) that will require the loading of an
+ * ICU data file.
+ * This function is not thread-safe. Use it before calling ICU APIs from
+ * multiple threads.
+ *
+ * @param directory The directory to be set.
+ *
+ * @see u_init
  * @stable ICU 2.0
  */
 U_CAPI void U_EXPORT2 u_setDataDirectory(const char *directory);