ICU-770 Add documentation

X-SVN-Rev: 5463

icu4c/source/common/unicode/uclean.h

@@ -19,6 +19,36 @@
 
 #include "unicode/utypes.h"
 
+/**
+ * Clean up the system resources, such as allocated memory or open files,
+ * used in all ICU libraries. This will free/delete all memory owned by the
+ * ICU libraries, and return them to their original load state. All open ICU
+ * items (collators, resource bundles, converters, etc.) must be closed before
+ * calling this function, otherwise ICU may not free its allocated memory
+ * (e.g. close your converters and resource bundles before calling this
+ * function). Generally, this function should be called once just before
+ * an application exits. For applications that dynamically load and unload
+ * the ICU libraries (relatively uncommon), u_cleanup() should be called
+ * just before the library unload.
+ * <p>
+ * u_cleanup() is not thread safe.  All other threads should stop using ICU
+ * before calling this function.
+ * <p>
+ * Any open ICU items will be left in an undefined state by u_cleanup(),
+ * and any subsequent attempt to use such an item will give unpredictable
+ * results.
+ * <p>
+ * After calling u_cleanup(), an application may continue to use ICU by
+ * creating an ICU C++ object or opening new items (converters, collators,
+ * etc.) and using them.
+ * <p>
+ * The use of u_cleanup() just before an application terminates is optional,
+ * but it should be called only once for performance reasons. The primary
+ * benefit is to eliminate reports of memory or resource leaks originating
+ * in ICU code from the results generated by heap analysis tools.
+ *
+ * @draft
+ */
 U_CAPI void U_EXPORT2 u_cleanup(void);
 
 #endif