summaryrefslogtreecommitdiff
path: root/qemu-coroutine.c
blob: 423430d3a032b78bc69cd0032108174b1f9173f7 (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
/*
 * QEMU coroutines
 *
 * Copyright IBM, Corp. 2011
 *
 * Authors:
 *  Stefan Hajnoczi    <stefanha@linux.vnet.ibm.com>
 *  Kevin Wolf         <kwolf@redhat.com>
 *
 * This work is licensed under the terms of the GNU LGPL, version 2 or later.
 * See the COPYING.LIB file in the top-level directory.
 *
 */

#include "trace.h"
#include "qemu-common.h"
#include "qemu/thread.h"
#include "block/coroutine.h"
#include "block/coroutine_int.h"

enum {
    /* Maximum free pool size prevents holding too many freed coroutines */
    POOL_MAX_SIZE = 64,
};

/** Free list to speed up creation */
static QemuMutex pool_lock;
static QSLIST_HEAD(, Coroutine) pool = QSLIST_HEAD_INITIALIZER(pool);
static unsigned int pool_size;

Coroutine *qemu_coroutine_create(CoroutineEntry *entry)
{
    Coroutine *co;

    qemu_mutex_lock(&pool_lock);
    co = QSLIST_FIRST(&pool);
    if (co) {
        QSLIST_REMOVE_HEAD(&pool, pool_next);
        pool_size--;
    }
    qemu_mutex_unlock(&pool_lock);

    if (!co) {
        co = qemu_coroutine_new();
    }

    co->entry = entry;
    QTAILQ_INIT(&co->co_queue_wakeup);
    return co;
}

static void coroutine_delete(Coroutine *co)
{
    qemu_mutex_lock(&pool_lock);
    if (pool_size < POOL_MAX_SIZE) {
        QSLIST_INSERT_HEAD(&pool, co, pool_next);
        co->caller = NULL;
        pool_size++;
        qemu_mutex_unlock(&pool_lock);
        return;
    }
    qemu_mutex_unlock(&pool_lock);

    qemu_coroutine_delete(co);
}

static void __attribute__((constructor)) coroutine_pool_init(void)
{
    qemu_mutex_init(&pool_lock);
}

static void __attribute__((destructor)) coroutine_pool_cleanup(void)
{
    Coroutine *co;
    Coroutine *tmp;

    QSLIST_FOREACH_SAFE(co, &pool, pool_next, tmp) {
        QSLIST_REMOVE_HEAD(&pool, pool_next);
        qemu_coroutine_delete(co);
    }

    qemu_mutex_destroy(&pool_lock);
}

static void coroutine_swap(Coroutine *from, Coroutine *to)
{
    CoroutineAction ret;

    ret = qemu_coroutine_switch(from, to, COROUTINE_YIELD);

    qemu_co_queue_run_restart(to);

    switch (ret) {
    case COROUTINE_YIELD:
        return;
    case COROUTINE_TERMINATE:
        trace_qemu_coroutine_terminate(to);
        coroutine_delete(to);
        return;
    default:
        abort();
    }
}

void qemu_coroutine_enter(Coroutine *co, void *opaque)
{
    Coroutine *self = qemu_coroutine_self();

    trace_qemu_coroutine_enter(self, co, opaque);

    if (co->caller) {
        fprintf(stderr, "Co-routine re-entered recursively\n");
        abort();
    }

    co->caller = self;
    co->entry_arg = opaque;
    coroutine_swap(self, co);
}

void coroutine_fn qemu_coroutine_yield(void)
{
    Coroutine *self = qemu_coroutine_self();
    Coroutine *to = self->caller;

    trace_qemu_coroutine_yield(self, to);

    if (!to) {
        fprintf(stderr, "Co-routine is yielding to no one\n");
        abort();
    }

    self->caller = NULL;
    coroutine_swap(self, to);
}