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Feature #3620 » thread.c

ko1 (Koichi Sasada), 08/29/2013 06:54 PM

 
#include <ruby.h>

enum {
CONDVAR_WAITERS = 0
};

enum {
QUEUE_QUE = 0,
QUEUE_WAITERS = 1,
SZQUEUE_WAITERS = 2,
SZQUEUE_MAX = 3
};

#define GET_CONDVAR_WAITERS(cv) RSTRUCT_GET((cv), CONDVAR_WAITERS)

#define GET_QUEUE_QUE(q) RSTRUCT_GET((q), QUEUE_QUE)
#define GET_QUEUE_WAITERS(q) RSTRUCT_GET((q), QUEUE_WAITERS)
#define GET_SZQUEUE_WAITERS(q) RSTRUCT_GET((q), SZQUEUE_WAITERS)
#define GET_SZQUEUE_MAX(q) RSTRUCT_GET((q), SZQUEUE_MAX)
#define GET_SZQUEUE_ULONGMAX(q) NUM2ULONG(GET_SZQUEUE_MAX(q))

static VALUE
ary_buf_new(void)
{
return rb_ary_tmp_new(1);
}

static void
wakeup_first_thread(VALUE list)
{
VALUE thread;

while (!NIL_P(thread = rb_ary_shift(list))) {
if (RTEST(rb_thread_wakeup_alive(thread))) break;
}
}

static void
wakeup_all_threads(VALUE list)
{
VALUE thread;
long i;

for (i=0; i<RARRAY_LEN(list); i++) {
thread = RARRAY_AREF(list, i);
rb_thread_wakeup_alive(thread);
}
rb_ary_clear(list);
}

/*
* Document-class: ConditionVariable
*
* ConditionVariable objects augment class Mutex. Using condition variables,
* it is possible to suspend while in the middle of a critical section until a
* resource becomes available.
*
* Example:
*
* require 'thread'
*
* mutex = Mutex.new
* resource = ConditionVariable.new
*
* a = Thread.new {
* mutex.synchronize {
* # Thread 'a' now needs the resource
* resource.wait(mutex)
* # 'a' can now have the resource
* }
* }
*
* b = Thread.new {
* mutex.synchronize {
* # Thread 'b' has finished using the resource
* resource.signal
* }
* }
*/

/*
* Document-method: new
* call-seq: new
*
* Creates a new condvar.
*/

static VALUE
rb_condvar_initialize(VALUE self)
{
RSTRUCT_SET(self, CONDVAR_WAITERS, ary_buf_new());
return self;
}

struct sleep_call {
VALUE mutex;
VALUE timeout;
};

static VALUE
do_sleep(VALUE args)
{
struct sleep_call *p = (struct sleep_call *)args;
return rb_mutex_sleep(p->mutex, p->timeout);
}

static VALUE
delete_current_thread(VALUE ary)
{
return rb_ary_delete(ary, rb_thread_current());
}

/*
* Document-method: wait
* call-seq: wait(mutex, timeout=nil)
*
* Releases the lock held in +mutex+ and waits; reacquires the lock on wakeup.
*
* If +timeout+ is given, this method returns after +timeout+ seconds passed,
* even if no other thread doesn't signal.
*/

static VALUE
rb_condvar_wait(int argc, VALUE *argv, VALUE self)
{
VALUE waiters = GET_CONDVAR_WAITERS(self);
VALUE mutex, timeout;
struct sleep_call args;

rb_scan_args(argc, argv, "11", &mutex, &timeout);

args.mutex = mutex;
args.timeout = timeout;
rb_ary_push(waiters, rb_thread_current());
rb_ensure(do_sleep, (VALUE)&args, delete_current_thread, waiters);

return self;
}

/*
* Document-method: signal
* call-seq: signal
*
* Wakes up the first thread in line waiting for this lock.
*/

static VALUE
rb_condvar_signal(VALUE self)
{
wakeup_first_thread(GET_CONDVAR_WAITERS(self));
return self;
}

/*
* Document-method: broadcast
* call-seq: broadcast
*
* Wakes up all threads waiting for this lock.
*/

static VALUE
rb_condvar_broadcast(VALUE self)
{
wakeup_all_threads(GET_CONDVAR_WAITERS(self));
return self;
}

/*
* Document-class: Queue
*
* This class provides a way to synchronize communication between threads.
*
* Example:
*
* require 'thread'
* queue = Queue.new
*
* producer = Thread.new do
* 5.times do |i|
* sleep rand(i) # simulate expense
* queue << i
* puts "#{i} produced"
* end
* end
*
* consumer = Thread.new do
* 5.times do |i|
* value = queue.pop
* sleep rand(i/2) # simulate expense
* puts "consumed #{value}"
* end
* end
*
*/

/*
* Document-method: new
* call-seq: new
*
* Creates a new queue.
*/

static VALUE
rb_queue_initialize(VALUE self)
{
RSTRUCT_SET(self, QUEUE_QUE, ary_buf_new());
RSTRUCT_SET(self, QUEUE_WAITERS, ary_buf_new());
return self;
}

static VALUE
queue_do_push(VALUE self, VALUE obj)
{
rb_ary_push(GET_QUEUE_QUE(self), obj);
wakeup_first_thread(GET_QUEUE_WAITERS(self));
return self;
}

/*
* Document-method: push
* call-seq: push(obj)
*
* Pushes +obj+ to the queue.
*/

static VALUE
rb_queue_push(VALUE self, VALUE obj)
{
return queue_do_push(self, obj);
}

static unsigned long
queue_length(VALUE self)
{
return RARRAY_LEN(GET_QUEUE_QUE(self));
}

static unsigned long
queue_num_waiting(VALUE self)
{
return RARRAY_LEN(GET_QUEUE_WAITERS(self));
}

struct waiting_delete {
VALUE waiting;
VALUE th;
};

static VALUE
queue_delete_from_waiting(struct waiting_delete *p)
{
rb_ary_delete(p->waiting, p->th);
return Qnil;
}

static VALUE
queue_do_pop(VALUE self, VALUE should_block)
{
struct waiting_delete args;
args.waiting = GET_QUEUE_WAITERS(self);
args.th = rb_thread_current();

while (queue_length(self) == 0) {
if (!(int)should_block) {
rb_raise(rb_eThreadError, "queue empty");
}
rb_ary_push(args.waiting, args.th);
rb_ensure((VALUE (*)())rb_thread_sleep_forever, (VALUE)0, queue_delete_from_waiting, (VALUE)&args);
}

return rb_ary_shift(GET_QUEUE_QUE(self));
}

static VALUE
queue_pop_should_block(int argc, VALUE *argv)
{
VALUE should_block = Qtrue;
switch (argc) {
case 0:
break;
case 1:
should_block = RTEST(argv[0]) ? Qtrue : Qfalse;
break;
default:
rb_raise(rb_eArgError, "wrong number of arguments (%d for 1)", argc);
}
return should_block;
}

/*
* Document-method: pop
* call_seq: pop(non_block=false)
*
* Retrieves data from the queue. If the queue is empty, the calling thread is
* suspended until data is pushed onto the queue. If +non_block+ is true, the
* thread isn't suspended, and an exception is raised.
*/

static VALUE
rb_queue_pop(int argc, VALUE *argv, VALUE self)
{
VALUE should_block = queue_pop_should_block(argc, argv);
return queue_do_pop(self, should_block);
}

/*
* Document-method: empty?
* call-seq: empty?
*
* Returns +true+ if the queue is empty.
*/

static VALUE
rb_queue_empty_p(VALUE self)
{
return queue_length(self) == 0 ? Qtrue : Qfalse;
}

/*
* Document-method: clear
* call-seq: clear
*
* Removes all objects from the queue.
*/

static VALUE
rb_queue_clear(VALUE self)
{
rb_ary_clear(GET_QUEUE_QUE(self));
return self;
}

/*
* Document-method: length
* call-seq: length
*
* Returns the length of the queue.
*/

static VALUE
rb_queue_length(VALUE self)
{
unsigned long len = queue_length(self);
return ULONG2NUM(len);
}

/*
* Document-method: num_waiting
* call-seq: num_waiting
*
* Returns the number of threads waiting on the queue.
*/

static VALUE
rb_queue_num_waiting(VALUE self)
{
unsigned long len = queue_num_waiting(self);
return ULONG2NUM(len);
}

/*
* Document-class: SizedQueue
*
* This class represents queues of specified size capacity. The push operation
* may be blocked if the capacity is full.
*
* See Queue for an example of how a SizedQueue works.
*/

/*
* Document-method: new
* call-seq: new(max)
*
* Creates a fixed-length queue with a maximum size of +max+.
*/

static VALUE
rb_szqueue_initialize(VALUE self, VALUE vmax)
{
long max;

max = NUM2LONG(vmax);
if (max <= 0) {
rb_raise(rb_eArgError, "queue size must be positive");
}

RSTRUCT_SET(self, QUEUE_QUE, ary_buf_new());
RSTRUCT_SET(self, QUEUE_WAITERS, ary_buf_new());
RSTRUCT_SET(self, SZQUEUE_WAITERS, ary_buf_new());
RSTRUCT_SET(self, SZQUEUE_MAX, vmax);

return self;
}

/*
* Document-method: max
* call-seq: max
*
* Returns the maximum size of the queue.
*/

static VALUE
rb_szqueue_max_get(VALUE self)
{
return GET_SZQUEUE_MAX(self);
}

/*
* Document-method: max=
* call-seq: max=(n)
*
* Sets the maximum size of the queue.
*/

static VALUE
rb_szqueue_max_set(VALUE self, VALUE vmax)
{
long max = NUM2LONG(vmax), diff = 0;
VALUE t;

if (max <= 0) {
rb_raise(rb_eArgError, "queue size must be positive");
}
if ((unsigned long)max > GET_SZQUEUE_ULONGMAX(self)) {
diff = max - GET_SZQUEUE_ULONGMAX(self);
}
RSTRUCT_SET(self, SZQUEUE_MAX, vmax);
while (diff > 0 && !NIL_P(t = rb_ary_shift(GET_QUEUE_QUE(self)))) {
rb_thread_wakeup_alive(t);
}
return vmax;
}

/*
* Document-method: push
* call-seq: push(obj)
*
* Pushes +obj+ to the queue. If there is no space left in the queue, waits
* until space becomes available.
*/

static VALUE
rb_szqueue_push(VALUE self, VALUE obj)
{
struct waiting_delete args;
args.waiting = GET_QUEUE_WAITERS(self);
args.th = rb_thread_current();

while (queue_length(self) >= GET_SZQUEUE_ULONGMAX(self)) {
rb_ary_push(args.waiting, args.th);
rb_ensure((VALUE (*)())rb_thread_sleep_forever, (VALUE)0, queue_delete_from_waiting, (VALUE)&args);
}
return queue_do_push(self, obj);
}

static VALUE
szqueue_do_pop(VALUE self, VALUE should_block)
{
VALUE retval = queue_do_pop(self, should_block);

if (queue_length(self) < GET_SZQUEUE_ULONGMAX(self)) {
wakeup_first_thread(GET_SZQUEUE_WAITERS(self));
}

return retval;
}

/*
* Document-method: pop
* call_seq: pop(non_block=false)
*
* Returns the number of threads waiting on the queue.
*/

static VALUE
rb_szqueue_pop(int argc, VALUE *argv, VALUE self)
{
VALUE should_block = queue_pop_should_block(argc, argv);
return szqueue_do_pop(self, should_block);
}

/*
* Document-method: pop
* call_seq: pop(non_block=false)
*
* Returns the number of threads waiting on the queue.
*/

static VALUE
rb_szqueue_num_waiting(VALUE self)
{
long len = queue_num_waiting(self);
len += RARRAY_LEN(GET_SZQUEUE_WAITERS(self));
return ULONG2NUM(len);
}

#ifndef UNDER_THREAD
#define UNDER_THREAD 1
#endif

void
Init_thread(void)
{
#if UNDER_THREAD
#define ALIAS_GLOBCAL_CONST(name) do { \
ID id = rb_intern_const(#name); \
if (!rb_const_defined_at(rb_cObject, id)) { \
rb_const_set(rb_cObject, id, rb_c##name); \
} \
} while (0)
#else
#define ALIAS_GLOBCAL_CONST(name) do { /* nothing */ } while (0)
#endif

VALUE rb_cConditionVariable = rb_struct_define_without_accessor_under(
UNDER_THREAD ? rb_cThread : 0,
"ConditionVariable", rb_cObject, rb_struct_alloc_noinit,
"waiters", NULL);
VALUE rb_cQueue = rb_struct_define_without_accessor_under(
UNDER_THREAD ? rb_cThread : 0,
"Queue", rb_cObject, rb_struct_alloc_noinit,
"que", "waiters", NULL);
VALUE rb_cSizedQueue = rb_struct_define_without_accessor_under(
UNDER_THREAD ? rb_cThread : 0,
"SizedQueue", rb_cQueue, rb_struct_alloc_noinit,
"que", "waiters", "queue_waiters", "size", NULL);

rb_define_method(rb_cConditionVariable, "initialize", rb_condvar_initialize, 0);
rb_define_method(rb_cConditionVariable, "wait", rb_condvar_wait, -1);
rb_define_method(rb_cConditionVariable, "signal", rb_condvar_signal, 0);
rb_define_method(rb_cConditionVariable, "broadcast", rb_condvar_broadcast, 0);

rb_define_method(rb_cQueue, "initialize", rb_queue_initialize, 0);
rb_define_method(rb_cQueue, "push", rb_queue_push, 1);
rb_define_method(rb_cQueue, "pop", rb_queue_pop, -1);
rb_define_method(rb_cQueue, "empty?", rb_queue_empty_p, 0);
rb_define_method(rb_cQueue, "clear", rb_queue_clear, 0);
rb_define_method(rb_cQueue, "length", rb_queue_length, 0);
rb_define_method(rb_cQueue, "num_waiting", rb_queue_num_waiting, 0);

rb_alias(rb_cQueue, rb_intern("enq"), rb_intern("push"));
rb_alias(rb_cQueue, rb_intern("<<"), rb_intern("push"));
rb_alias(rb_cQueue, rb_intern("deq"), rb_intern("pop"));
rb_alias(rb_cQueue, rb_intern("shift"), rb_intern("pop"));
rb_alias(rb_cQueue, rb_intern("size"), rb_intern("length"));

rb_define_method(rb_cSizedQueue, "initialize", rb_szqueue_initialize, 1);
rb_define_method(rb_cSizedQueue, "max", rb_szqueue_max_get, 0);
rb_define_method(rb_cSizedQueue, "max=", rb_szqueue_max_set, 1);
rb_define_method(rb_cSizedQueue, "push", rb_szqueue_push, 1);
rb_define_method(rb_cSizedQueue, "pop", rb_szqueue_pop, -1);
rb_define_method(rb_cSizedQueue, "num_waiting", rb_szqueue_num_waiting, 0);
rb_alias(rb_cSizedQueue, rb_intern("enq"), rb_intern("push"));
rb_alias(rb_cSizedQueue, rb_intern("<<"), rb_intern("push"));
rb_alias(rb_cSizedQueue, rb_intern("deq"), rb_intern("pop"));
rb_alias(rb_cSizedQueue, rb_intern("shift"), rb_intern("pop"));

rb_provide("thread.rb");
ALIAS_GLOBCAL_CONST(ConditionVariable);
ALIAS_GLOBCAL_CONST(Queue);
ALIAS_GLOBCAL_CONST(SizedQueue);
}
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