1 files changed, 155 insertions, 0 deletions
diff --git a/src/vppinfra/timing_wheel.h b/src/vppinfra/timing_wheel.h
new file mode 100644
index 00000000000..7daea994248
--- /dev/null
+++ b/src/vppinfra/timing_wheel.h
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+/*
+ * Copyright (c) 2015 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.
+ */
+#ifndef included_clib_timing_wheel_h
+#define included_clib_timing_wheel_h
+
+#include <vppinfra/format.h>
+
+typedef struct
+{
+  /* Time of this element in units cpu clock ticks relative to time
+     base. 32 bits should be large enough for serveral kilo-seconds
+     to elapse before we have to re-set time base. */
+  u32 cpu_time_relative_to_base;
+
+  /* User data to store in this bin. */
+  u32 user_data;
+} timing_wheel_elt_t;
+
+/* Overflow wheel elements where time does not fit into 32 bits. */
+typedef struct
+{
+  /* Absolute time of this element. */
+  u64 cpu_time;
+
+  /* User data to store in this bin. */
+  u32 user_data;
+
+  u32 pad;
+} timing_wheel_overflow_elt_t;
+
+typedef struct
+{
+  /* 2^M bits: 1 means vector is non-zero else zero. */
+  uword *occupancy_bitmap;
+
+  /* 2^M element table of element vectors, one for each time bin. */
+  timing_wheel_elt_t **elts;
+} timing_wheel_level_t;
+
+typedef struct
+{
+  /* Vector of refill counts per level. */
+  u64 *refills;
+
+  /* Number of times cpu time base was rescaled. */
+  u64 cpu_time_base_advances;
+} timing_wheel_stats_t;
+
+typedef struct
+{
+  /* Each bin is a power of two clock ticks (N)
+     chosen so that 2^N >= min_sched_time. */
+  u8 log2_clocks_per_bin;
+
+  /* Wheels are 2^M bins where 2^(N+M) >= max_sched_time. */
+  u8 log2_bins_per_wheel;
+
+  /* N + M. */
+  u8 log2_clocks_per_wheel;
+
+  /* Number of bits to use in cpu_time_relative_to_base field
+     of timing_wheel_elt_t. */
+  u8 n_wheel_elt_time_bits;
+
+  /* 2^M. */
+  u32 bins_per_wheel;
+
+  /* 2^M - 1. */
+  u32 bins_per_wheel_mask;
+
+  timing_wheel_level_t *levels;
+
+  timing_wheel_overflow_elt_t *overflow_pool;
+
+  /* Free list of element vector so we can recycle old allocated vectors. */
+  timing_wheel_elt_t **free_elt_vectors;
+
+  timing_wheel_elt_t *unexpired_elts_pending_insert;
+
+  /* Hash table of user data values which have been deleted but not yet re-inserted. */
+  uword *deleted_user_data_hash;
+
+  /* Enable validation for debugging. */
+  u32 validate;
+
+  /* Time index.  Measures time in units of 2^N clock ticks from
+     when wheel starts. */
+  u64 current_time_index;
+
+  /* All times are 32 bit numbers relative to cpu_time_base.
+     So, roughly every 2^(32 + N) clocks we'll need to subtract from
+     all timing_wheel_elt_t times to make sure they never overflow. */
+  u64 cpu_time_base;
+
+  /* When current_time_index is >= this we update cpu_time_base
+     to avoid overflowing 32 bit cpu_time_relative_to_base
+     in timing_wheel_elt_t. */
+  u64 time_index_next_cpu_time_base_update;
+
+  /* Cached earliest element on wheel; 0 if not valid. */
+  u64 cached_min_cpu_time_on_wheel;
+
+  f64 min_sched_time, max_sched_time, cpu_clocks_per_second;
+
+  timing_wheel_stats_t stats;
+} timing_wheel_t;
+
+/* Initialization function. */
+void timing_wheel_init (timing_wheel_t * w,
+			u64 current_cpu_time, f64 cpu_clocks_per_second);
+
+/* Insert user data on wheel at given CPU time stamp. */
+void timing_wheel_insert (timing_wheel_t * w, u64 insert_cpu_time,
+			  u32 user_data);
+
+/* Delete user data from wheel (until it is again inserted). */
+void timing_wheel_delete (timing_wheel_t * w, u32 user_data);
+
+/* Advance wheel and return any expired user data in vector.  If non-zero
+   min_next_expiring_element_cpu_time will return a cpu time stamp
+   before which there are guaranteed to be no elements in the current wheel. */
+u32 *timing_wheel_advance (timing_wheel_t * w, u64 advance_cpu_time,
+			   u32 * expired_user_data,
+			   u64 * min_next_expiring_element_cpu_time);
+
+/* Returns absolute time in clock cycles of next expiring element. */
+u64 timing_wheel_next_expiring_elt_time (timing_wheel_t * w);
+
+/* Format a timing wheel. */
+format_function_t format_timing_wheel;
+
+/* Testing function to validate wheel. */
+void timing_wheel_validate (timing_wheel_t * w);
+
+#endif /* included_clib_timing_wheel_h */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */