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// Copyright (c) 2014-2015, Loïc Hoguin <[email protected]>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#include "nif_helpers.h"
#include <sys/queue.h>
#include <stdarg.h>
extern ERL_NIF_TERM atom_ok;
extern ERL_NIF_TERM atom__nif_thread_ret_;
typedef struct nif_thread_message {
TAILQ_ENTRY(nif_thread_message) next_entry;
ErlNifPid* from_pid;
void* function;
nif_thread_arg* args;
} nif_thread_message;
typedef TAILQ_HEAD(nif_thread_mailbox, nif_thread_message) nif_thread_mailbox;
typedef struct {
ErlNifTid tid;
ErlNifMutex* lock;
ErlNifCond* cond;
nif_thread_mailbox* mailbox;
} nif_thread_state;
// Message.
static nif_thread_message* nif_thread_message_alloc(void* f, nif_thread_arg* args, ErlNifPid* pid)
{
nif_thread_message* msg = (nif_thread_message*)enif_alloc(sizeof(nif_thread_message));
msg->from_pid = pid;
msg->function = f;
msg->args = args;
return msg;
}
static void nif_thread_message_free(nif_thread_message* msg)
{
enif_free(msg->from_pid);
enif_free(msg->args);
enif_free(msg);
}
// Calls and casts.
static ERL_NIF_TERM nif_thread_send(nif_thread_state* st, nif_thread_message* msg)
{
enif_mutex_lock(st->lock);
TAILQ_INSERT_TAIL(st->mailbox, msg, next_entry);
enif_cond_signal(st->cond);
enif_mutex_unlock(st->lock);
return atom_ok;
}
ERL_NIF_TERM nif_thread_cast(ErlNifEnv* env, void (*f)(nif_thread_arg*), int a, ...)
{
va_list ap;
int i;
nif_thread_arg* args = (nif_thread_arg*)enif_alloc(a * sizeof(nif_thread_arg));
va_start(ap, a);
for (i = 0; i < a; i++)
args[i] = va_arg(ap, void*);
va_end(ap);
nif_thread_message* msg = nif_thread_message_alloc(f, args, NULL);
return nif_thread_send((nif_thread_state*)enif_priv_data(env), msg);
}
ERL_NIF_TERM nif_thread_call(ErlNifEnv* env, ERL_NIF_TERM (*f)(ErlNifEnv*, nif_thread_arg*), int a, ...)
{
va_list ap;
int i;
nif_thread_arg* args = (nif_thread_arg*)enif_alloc(a * sizeof(nif_thread_arg));
va_start(ap, a);
for (i = 0; i < a; i++)
args[i] = va_arg(ap, void*);
va_end(ap);
ErlNifPid* pid = (ErlNifPid*)enif_alloc(sizeof(ErlNifPid));
nif_thread_message* msg = nif_thread_message_alloc((void*)f, args, enif_self(env, pid));
return nif_thread_send((nif_thread_state*)enif_priv_data(env), msg);
}
// Main thread loop.
static int nif_thread_receive(nif_thread_state* st, nif_thread_message** msg)
{
enif_mutex_lock(st->lock);
while (TAILQ_EMPTY(st->mailbox))
enif_cond_wait(st->cond, st->lock);
*msg = TAILQ_FIRST(st->mailbox);
TAILQ_REMOVE(st->mailbox, TAILQ_FIRST(st->mailbox), next_entry);
enif_mutex_unlock(st->lock);
if ((*msg)->function == NULL)
return 0;
return 1;
}
static void nif_thread_handle(ErlNifEnv* env, nif_thread_state* st, nif_thread_message* msg)
{
if (msg->from_pid == NULL) {
void (*cast)(nif_thread_arg*) = msg->function;
cast(msg->args);
} else {
ERL_NIF_TERM (*call)(ErlNifEnv*, nif_thread_arg*) = msg->function;
ERL_NIF_TERM ret = call(env, msg->args);
enif_send(NULL, msg->from_pid, env,
enif_make_tuple2(env, atom__nif_thread_ret_, ret));
enif_clear_env(env);
}
nif_thread_message_free(msg);
}
static void* nif_main_thread(void* obj)
{
ErlNifEnv* env = enif_alloc_env();
nif_thread_state* st = (nif_thread_state*)obj;
nif_thread_message* msg;
while (nif_thread_receive(st, &msg))
nif_thread_handle(env, st, msg);
enif_free_env(env);
return NULL;
}
// Main thread creation/destruction.
void* nif_create_main_thread(char* name)
{
nif_thread_state* st = (nif_thread_state*)enif_alloc(sizeof(nif_thread_state));
st->lock = enif_mutex_create("nif_thread_mailbox_lock");
st->cond = enif_cond_create("nif_thread_mailbox_cond");
st->mailbox = (nif_thread_mailbox*)enif_alloc(sizeof(nif_thread_mailbox));
TAILQ_INIT(st->mailbox);
#if defined(__APPLE__) && defined(__MACH__)
// On OSX we identify ourselves as the main thread to ensure that
// we are compatible with libraries that require it. For example
// this is necessary with SDL2 in order to receive input events.
erl_drv_steal_main_thread(name, &(st->tid), nif_main_thread, st, NULL);
#else
enif_thread_create(name, &(st->tid), nif_main_thread, st, NULL);
#endif
return (void*)st;
}
void nif_destroy_main_thread(void* void_st)
{
nif_thread_state* st = (nif_thread_state*)void_st;
nif_thread_message* msg = nif_thread_message_alloc(NULL, NULL, NULL);
nif_thread_send(st, msg);
enif_thread_join(st->tid, NULL);
enif_cond_destroy(st->cond);
enif_mutex_destroy(st->lock);
enif_free(st->mailbox);
enif_free(st);
}
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