host stack: update stale copyright

[vpp.git] / src / svm / queue.h

diff --git a/src/svm/queue.h b/src/svm/queue.h
index 68a63d7..2630f17 100644 (file)
--- a/src/svm/queue.h
+++ b/src/svm/queue.h
@@ -2,7 +2,7 @@
  *------------------------------------------------------------------
  * svm_queue.h - shared-memory queues
  *
- * Copyright (c) 2009 Cisco and/or its affiliates.
+ * Copyright (c) 2009-2019 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:
@@ -32,32 +32,44 @@ typedef struct _svm_queue
   int maxsize;
   int elsize;
   int consumer_pid;
-  int signal_when_queue_non_empty;
+  int producer_evtfd;
+  int consumer_evtfd;
   char data[0];
 } svm_queue_t;
 
 typedef enum
 {
-  /**
-   * blocking call
-   */
-  SVM_Q_WAIT = 0,
-
-  /**
-   * non-blocking call
-   */
-  SVM_Q_NOWAIT,
-
-  /**
-   * blocking call, return on signal or time-out
-   */
-  SVM_Q_TIMEDWAIT,
+  SVM_Q_WAIT = 0,      /**< blocking call - best used in combination with
+                            condvars, for eventfds we don't yield the cpu */
+  SVM_Q_NOWAIT,                /**< non-blocking call - works with both condvar and
+                            eventfd signaling */
+  SVM_Q_TIMEDWAIT,     /**< blocking call, returns on signal or time-out -
+                            best used in combination with condvars, with
+                            eventfds we don't yield the cpu */
 } svm_q_conditional_wait_t;
 
-svm_queue_t *svm_queue_init (int nels,
-                            int elsize,
-                            int consumer_pid,
-                            int signal_when_queue_non_empty);
+/**
+ * Allocate and initialize svm queue
+ *
+ * @param nels         number of elements on the queue
+ * @param elsize       element size, presumably 4 and cacheline-size will
+ *                     be popular choices.
+ * @param pid          consumer pid
+ * @return             a newly initialized svm queue
+ *
+ * The idea is to call this function in the queue consumer,
+ * and e-mail the queue pointer to the producer(s).
+ *
+ * The vpp process / main thread allocates one of these
+ * at startup; its main input queue. The vpp main input queue
+ * has a pointer to it in the shared memory segment header.
+ *
+ * You probably want to be on an svm data heap before calling this
+ * function.
+ */
+svm_queue_t *svm_queue_alloc_and_init (int nels, int elsize,
+                                      int consumer_pid);
+svm_queue_t *svm_queue_init (void *base, int nels, int elsize);
 void svm_queue_free (svm_queue_t * q);
 int svm_queue_add (svm_queue_t * q, u8 * elem, int nowait);
 int svm_queue_add2 (svm_queue_t * q, u8 * elem, u8 * elem2, int nowait);
@@ -70,6 +82,24 @@ int svm_queue_is_full (svm_queue_t * q);
 int svm_queue_add_nolock (svm_queue_t * q, u8 * elem);
 int svm_queue_sub_raw (svm_queue_t * q, u8 * elem);
 
+/**
+ * Wait for queue event
+ *
+ * Must be called with mutex held.
+ */
+void svm_queue_wait (svm_queue_t * q);
+
+/**
+ * Timed wait for queue event
+ *
+ * Must be called with mutex held.
+ *
+ * @param q            svm queue
+ * @param timeout      time in seconds
+ * @return             0 on success, ETIMEDOUT on timeout or an error
+ */
+int svm_queue_timedwait (svm_queue_t * q, double timeout);
+
 /**
  * Add element to queue with mutex held
  * @param q            queue
@@ -77,6 +107,25 @@ int svm_queue_sub_raw (svm_queue_t * q, u8 * elem);
  */
 void svm_queue_add_raw (svm_queue_t * q, u8 * elem);
 
+/**
+ * Set producer's event fd
+ *
+ * When the producer must generate an event it writes 1 to the provided fd.
+ * Once this is set, condvars are not used anymore for signaling.
+ */
+void svm_queue_set_producer_event_fd (svm_queue_t * q, int fd);
+
+/**
+ * Set consumer's event fd
+ *
+ * When the consumer must generate an event it writes 1 to the provided fd.
+ * Although in practice the two fds point to the same underlying file
+ * description, because the producer and consumer are different processes
+ * the descriptors will be different. It's the caller's responsibility to
+ * ensure the file descriptors are properly exchanged between the two peers.
+ */
+void svm_queue_set_consumer_event_fd (svm_queue_t * q, int fd);
+
 /*
  * DEPRECATED please use svm_queue_t instead
  */