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+/*
+ * Copyright (c) 2019 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/** @file
+ * @brief Callback multiplex scheme
+ * For a fully worked-out example, see .../src/vlib/main.[ch] and
+ * .../src/plugins/perfmon.c
+ */
+
+#ifndef included_callback_h
+#define included_callback_h
+#include <vppinfra/clib.h>
+
+/** @brief Add or remove a callback to the specified callback set
+ * @param h head of the callback vector
+ * @param tmp vector to build result
+ * @param l clib_spinlock_t lock to protect the vector, may be 0
+ * @param f function to add or remove
+ * @param enable 1 adds f to the vector, 0 removes f from the vector
+ *
+ * Add or remove a callback from the indicated callback vector.
+ * Caller must provide locking to prevent > 1 concurrent writer
+ * Swaps the head of the callback vector and a tmp vector in one
+ * motion, after a write barrier to ensure that the write is atomic.
+ */
+#define clib_callback_enable_disable(h,tmp,l,f,enable) \
+do { \
+ void *tmp2; \
+ clib_spinlock_lock_if_init(&l); \
+ vec_reset_length(tmp); \
+ vec_append(tmp, h); \
+ if (enable) \
+ vec_add1 (tmp,(void *)f); \
+ else \
+ { \
+ int i; \
+ for (i = 0; i < vec_len (tmp); i++) \
+ if (((void *)tmp[i]) == (void *)f) \
+ { \
+ vec_delete (tmp, 1, i); \
+ break; \
+ } \
+ } \
+ tmp2 = h; \
+ CLIB_MEMORY_STORE_BARRIER(); \
+ h = tmp; \
+ tmp = tmp2; \
+ clib_spinlock_unlock_if_init(&l); \
+} while(0);
+
+/** @brief call the specified callback set
+ * @param h the callback set
+ * @param varargs additional callback parameters
+ */
+#define clib_call_callbacks(h, ... ) \
+do { \
+ /* \
+ * Note: fp exists to shut up gcc-6, which \
+ * produces a warning not seen with gcc-7 or 8 \
+ */ \
+ void (*fp)(void *a1, ...); \
+ int i; \
+ for (i = 0; i < vec_len (h); i++) \
+ { \
+ fp = (void *)(h[i]); \
+ (*fp) (__VA_ARGS__); \
+ } \
+ } while (0);
+
+/** @brief predicate function says whether the specified function is enabled
+ * @param h the callback set
+ * @param l clib_spinlock_t lock to protect the vector, may be 0
+ * @param f the function to search for
+ * @return 1 if the function is enabled, 0 if not
+ */
+#define clib_callback_is_set(h,l,f) \
+({ \
+ int _i; \
+ int _found = 0; \
+ clib_spinlock_lock_if_init(&l); \
+ for (_i = 0; _i < vec_len (h); _i++) \
+ if (((void *)h[_i]) == (void *) f) \
+ { \
+ _found=1; \
+ break; \
+ } \
+ clib_spinlock_unlock_if_init(&l); \
+ _found; \
+ })
+
+#endif /* included_callback_h */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */