aboutsummaryrefslogtreecommitdiffstats
path: root/src/svm/queue.h
blob: 3e8031e897b84da4073cd769a839b940e72c60d0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
/*
 *------------------------------------------------------------------
 * svm_queue.h - shared-memory queues
 *
 * Copyright (c) 2009 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_svm_queue_h
#define included_svm_queue_h

#include <pthread.h>

typedef struct _svm_queue
{
  pthread_mutex_t mutex;	/* 8 bytes */
  pthread_cond_t condvar;	/* 8 bytes */
  int head;
  int tail;
  volatile int cursize;
  int maxsize;
  int elsize;
  int consumer_pid;
  int producer_evtfd;
  int consumer_evtfd;
  char data[0];
} svm_queue_t;

typedef enum
{
  SVM_Q_WAIT = 0,	/**< blocking call - must be used only in combination
			     with condvars */
  SVM_Q_NOWAIT,		/**< non-blocking call - works with both condvar and
			     eventfd signaling */
  SVM_Q_TIMEDWAIT,	/**< blocking call, returns on signal or time-out -
			     must be used only in combination with condvars */
} svm_q_conditional_wait_t;

/**
 * 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);
int svm_queue_sub (svm_queue_t * q, u8 * elem, svm_q_conditional_wait_t cond,
		   u32 time);
int svm_queue_sub2 (svm_queue_t * q, u8 * elem);
void svm_queue_lock (svm_queue_t * q);
void svm_queue_unlock (svm_queue_t * q);
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
 * @param elem		pointer element data to add
 */
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
 */
typedef svm_queue_t unix_shared_memory_queue_t;

#endif /* included_svm_queue_h */

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */