Add yrmcds_cnt_shutdown() to interrupt yrmcds_cnt_recv().

counter.c

@@ -78,6 +78,15 @@ yrmcds_cnt_close(yrmcds_cnt* c) {
     return YRMCDS_OK;
 }
 
+yrmcds_error
+yrmcds_cnt_shutdown(yrmcds_cnt* c) {
+    if( c == NULL )
+        return YRMCDS_BAD_ARGUMENT;
+    if( shutdown(c->sock, SHUT_RD) == -1 )
+        return YRMCDS_SYSTEM_ERROR;
+    return YRMCDS_OK;
+}
+
 int
 yrmcds_cnt_fileno(yrmcds_cnt* c) {
     return c->sock;

yrmcds.h

@@ -880,6 +880,21 @@ yrmcds_cnt_connect(yrmcds_cnt* c, const char* node, uint16_t port);
 yrmcds_error
 yrmcds_cnt_close(yrmcds_cnt* c);
 
+/**
+ * Shutdown the receiving end of the socket.
+ * @param  c     A pointer to ::yrmcds_cnt.
+ * @return 0 if \p c is valid.  Other values indicate an error.
+ *
+ * This function simply calls \p shutdown system call with \p SHUT_RD .
+ * This can be used to interrupt a thread waiting in ::yrmcds_cnt_recv.
+ *
+ * Note that interrupted ::yrmcds_cnt_recv will return ::YRMCDS_DISCONNECTED.
+ *
+ * \see https://github.com/cybozu/libyrmcds/issues/8
+ */
+yrmcds_error
+yrmcds_cnt_shutdown(yrmcds_cnt* c);
+
 /**
  * Return the underlying socket in ::yrmcds_cnt.
  * @param  c     A pointer to ::yrmcds_cnt.