rust/src/libstd/sync.rs
2012-08-15 14:11:39 -04:00

1252 lines
42 KiB
Rust

// NB: transitionary, de-mode-ing.
#[forbid(deprecated_mode)];
#[forbid(deprecated_pattern)];
/**
* The concurrency primitives you know and love.
*
* Maybe once we have a "core exports x only to std" mechanism, these can be
* in std.
*/
export condvar, semaphore, mutex, mutex_with_condvars;
export rwlock, rwlock_with_condvars, rwlock_write_mode, rwlock_read_mode;
// FIXME (#3119) This shouldn't be a thing exported from core.
import unsafe::{Exclusive, exclusive};
/****************************************************************************
* Internals
****************************************************************************/
// Each waiting task receives on one of these.
#[doc(hidden)]
type wait_end = pipes::port_one<()>;
#[doc(hidden)]
type signal_end = pipes::chan_one<()>;
// A doubly-ended queue of waiting tasks.
#[doc(hidden)]
struct waitqueue { head: pipes::port<signal_end>;
tail: pipes::chan<signal_end>; }
fn new_waitqueue() -> waitqueue {
let (block_tail, block_head) = pipes::stream();
waitqueue { head: block_head, tail: block_tail }
}
// Signals one live task from the queue.
#[doc(hidden)]
fn signal_waitqueue(q: &waitqueue) -> bool {
// The peek is mandatory to make sure recv doesn't block.
if q.head.peek() {
// Pop and send a wakeup signal. If the waiter was killed, its port
// will have closed. Keep trying until we get a live task.
if pipes::try_send_one(q.head.recv(), ()) {
true
} else {
signal_waitqueue(q)
}
} else {
false
}
}
#[doc(hidden)]
fn broadcast_waitqueue(q: &waitqueue) -> uint {
let mut count = 0;
while q.head.peek() {
if pipes::try_send_one(q.head.recv(), ()) {
count += 1;
}
}
count
}
// The building-block used to make semaphores, mutexes, and rwlocks.
#[doc(hidden)]
struct sem_inner<Q> {
mut count: int;
waiters: waitqueue;
// Can be either unit or another waitqueue. Some sems shouldn't come with
// a condition variable attached, others should.
blocked: Q;
}
#[doc(hidden)]
enum sem<Q: send> = Exclusive<sem_inner<Q>>;
#[doc(hidden)]
fn new_sem<Q: send>(count: int, +q: Q) -> sem<Q> {
sem(exclusive(sem_inner {
mut count: count, waiters: new_waitqueue(), blocked: q }))
}
#[doc(hidden)]
fn new_sem_and_signal(count: int, num_condvars: uint)
-> sem<~[mut waitqueue]> {
let mut queues = ~[mut];
for num_condvars.times {
vec::push(queues, new_waitqueue());
}
new_sem(count, queues)
}
#[doc(hidden)]
impl<Q: send> &sem<Q> {
fn acquire() {
let mut waiter_nobe = none;
unsafe {
do (**self).with |state| {
state.count -= 1;
if state.count < 0 {
// Create waiter nobe.
let (signal_end, wait_end) = pipes::oneshot();
// Tell outer scope we need to block.
waiter_nobe = some(wait_end);
// Enqueue ourself.
state.waiters.tail.send(signal_end);
}
}
}
// Uncomment if you wish to test for sem races. Not valgrind-friendly.
/* for 1000.times { task::yield(); } */
// Need to wait outside the exclusive.
if waiter_nobe.is_some() {
let _ = pipes::recv_one(option::unwrap(waiter_nobe));
}
}
fn release() {
unsafe {
do (**self).with |state| {
state.count += 1;
if state.count <= 0 {
signal_waitqueue(&state.waiters);
}
}
}
}
}
// FIXME(#3154) move both copies of this into sem<Q>, and unify the 2 structs
#[doc(hidden)]
impl &sem<()> {
fn access<U>(blk: fn() -> U) -> U {
let mut release = none;
unsafe {
do task::unkillable {
self.acquire();
release = some(sem_release(self));
}
}
blk()
}
}
#[doc(hidden)]
impl &sem<~[mut waitqueue]> {
fn access<U>(blk: fn() -> U) -> U {
let mut release = none;
unsafe {
do task::unkillable {
self.acquire();
release = some(sem_and_signal_release(self));
}
}
blk()
}
}
// FIXME(#3136) should go inside of access()
#[doc(hidden)]
struct sem_release {
sem: &sem<()>;
new(sem: &sem<()>) { self.sem = sem; }
drop { self.sem.release(); }
}
#[doc(hidden)]
struct sem_and_signal_release {
sem: &sem<~[mut waitqueue]>;
new(sem: &sem<~[mut waitqueue]>) { self.sem = sem; }
drop { self.sem.release(); }
}
/// A mechanism for atomic-unlock-and-deschedule blocking and signalling.
struct condvar { priv sem: &sem<~[mut waitqueue]>; drop { } }
impl &condvar {
/**
* Atomically drop the associated lock, and block until a signal is sent.
*
* # Failure
* A task which is killed (i.e., by linked failure with another task)
* while waiting on a condition variable will wake up, fail, and unlock
* the associated lock as it unwinds.
*/
fn wait() { self.wait_on(0) }
/**
* As wait(), but can specify which of multiple condition variables to
* wait on. Only a signal_on() or broadcast_on() with the same condvar_id
* will wake this thread.
*
* The associated lock must have been initialised with an appropriate
* number of condvars. The condvar_id must be between 0 and num_condvars-1
* or else this call will fail.
*
* wait() is equivalent to wait_on(0).
*/
fn wait_on(condvar_id: uint) {
// Create waiter nobe.
let (signal_end, wait_end) = pipes::oneshot();
let mut wait_end = some(wait_end);
let mut signal_end = some(signal_end);
let mut reacquire = none;
let mut out_of_bounds = none;
unsafe {
do task::unkillable {
// Release lock, 'atomically' enqueuing ourselves in so doing.
do (**self.sem).with |state| {
if condvar_id < vec::len(state.blocked) {
// Drop the lock.
state.count += 1;
if state.count <= 0 {
signal_waitqueue(&state.waiters);
}
// Enqueue ourself to be woken up by a signaller.
let signal_end = option::swap_unwrap(&mut signal_end);
state.blocked[condvar_id].tail.send(signal_end);
} else {
out_of_bounds = some(vec::len(state.blocked));
}
}
// If yield checks start getting inserted anywhere, we can be
// killed before or after enqueueing. Deciding whether to
// unkillably reacquire the lock needs to happen atomically
// wrt enqueuing.
if out_of_bounds.is_none() {
reacquire = some(sem_and_signal_reacquire(self.sem));
}
}
}
do check_cvar_bounds(out_of_bounds, condvar_id, "cond.wait_on()") {
// Unconditionally "block". (Might not actually block if a
// signaller already sent -- I mean 'unconditionally' in contrast
// with acquire().)
let _ = pipes::recv_one(option::swap_unwrap(&mut wait_end));
}
// This is needed for a failing condition variable to reacquire the
// mutex during unwinding. As long as the wrapper (mutex, etc) is
// bounded in when it gets released, this shouldn't hang forever.
struct sem_and_signal_reacquire {
sem: &sem<~[mut waitqueue]>;
new(sem: &sem<~[mut waitqueue]>) { self.sem = sem; }
drop unsafe {
// Needs to succeed, instead of itself dying.
do task::unkillable {
self.sem.acquire();
}
}
}
}
/// Wake up a blocked task. Returns false if there was no blocked task.
fn signal() -> bool { self.signal_on(0) }
/// As signal, but with a specified condvar_id. See wait_on.
fn signal_on(condvar_id: uint) -> bool {
let mut out_of_bounds = none;
let mut result = false;
unsafe {
do (**self.sem).with |state| {
if condvar_id < vec::len(state.blocked) {
result = signal_waitqueue(&state.blocked[condvar_id]);
} else {
out_of_bounds = some(vec::len(state.blocked));
}
}
}
do check_cvar_bounds(out_of_bounds, condvar_id, "cond.signal_on()") {
result
}
}
/// Wake up all blocked tasks. Returns the number of tasks woken.
fn broadcast() -> uint { self.broadcast_on(0) }
/// As broadcast, but with a specified condvar_id. See wait_on.
fn broadcast_on(condvar_id: uint) -> uint {
let mut out_of_bounds = none;
let mut queue = none;
unsafe {
do (**self.sem).with |state| {
if condvar_id < vec::len(state.blocked) {
// To avoid :broadcast_heavy, we make a new waitqueue,
// swap it out with the old one, and broadcast on the
// old one outside of the little-lock.
queue = some(util::replace(&mut state.blocked[condvar_id],
new_waitqueue()));
} else {
out_of_bounds = some(vec::len(state.blocked));
}
}
}
do check_cvar_bounds(out_of_bounds, condvar_id, "cond.signal_on()") {
let queue = option::swap_unwrap(&mut queue);
broadcast_waitqueue(&queue)
}
}
}
// Checks whether a condvar ID was out of bounds, and fails if so, or does
// something else next on success.
#[inline(always)]
#[doc(hidden)]
fn check_cvar_bounds<U>(out_of_bounds: option<uint>, id: uint, act: &str,
blk: fn() -> U) -> U {
match out_of_bounds {
some(0) =>
fail fmt!("%s with illegal ID %u - this lock has no condvars!",
act, id),
some(length) =>
fail fmt!("%s with illegal ID %u - ID must be less than %u",
act, id, length),
none => blk()
}
}
#[doc(hidden)]
impl &sem<~[mut waitqueue]> {
// The only other place that condvars get built is rwlock_write_mode.
fn access_cond<U>(blk: fn(c: &condvar) -> U) -> U {
do self.access { blk(&condvar { sem: self }) }
}
}
/****************************************************************************
* Semaphores
****************************************************************************/
/// A counting, blocking, bounded-waiting semaphore.
struct semaphore { priv sem: sem<()>; }
/// Create a new semaphore with the specified count.
fn semaphore(count: int) -> semaphore {
semaphore { sem: new_sem(count, ()) }
}
impl &semaphore {
/// Create a new handle to the semaphore.
fn clone() -> semaphore { semaphore { sem: sem((*self.sem).clone()) } }
/**
* Acquire a resource represented by the semaphore. Blocks if necessary
* until resource(s) become available.
*/
fn acquire() { (&self.sem).acquire() }
/**
* Release a held resource represented by the semaphore. Wakes a blocked
* contending task, if any exist. Won't block the caller.
*/
fn release() { (&self.sem).release() }
/// Run a function with ownership of one of the semaphore's resources.
fn access<U>(blk: fn() -> U) -> U { (&self.sem).access(blk) }
}
/****************************************************************************
* Mutexes
****************************************************************************/
/**
* A blocking, bounded-waiting, mutual exclusion lock with an associated
* FIFO condition variable.
*
* # Failure
* A task which fails while holding a mutex will unlock the mutex as it
* unwinds.
*/
struct mutex { priv sem: sem<~[mut waitqueue]>; }
/// Create a new mutex, with one associated condvar.
fn mutex() -> mutex { mutex_with_condvars(1) }
/**
* Create a new mutex, with a specified number of associated condvars. This
* will allow calling wait_on/signal_on/broadcast_on with condvar IDs between
* 0 and num_condvars-1. (If num_condvars is 0, lock_cond will be allowed but
* any operations on the condvar will fail.)
*/
fn mutex_with_condvars(num_condvars: uint) -> mutex {
mutex { sem: new_sem_and_signal(1, num_condvars) }
}
impl &mutex {
/// Create a new handle to the mutex.
fn clone() -> mutex { mutex { sem: sem((*self.sem).clone()) } }
/// Run a function with ownership of the mutex.
fn lock<U>(blk: fn() -> U) -> U { (&self.sem).access(blk) }
/// Run a function with ownership of the mutex and a handle to a condvar.
fn lock_cond<U>(blk: fn(c: &condvar) -> U) -> U {
(&self.sem).access_cond(blk)
}
}
/****************************************************************************
* Reader-writer locks
****************************************************************************/
// NB: Wikipedia - Readers-writers_problem#The_third_readers-writers_problem
#[doc(hidden)]
struct rwlock_inner {
read_mode: bool;
read_count: uint;
}
/**
* A blocking, no-starvation, reader-writer lock with an associated condvar.
*
* # Failure
* A task which fails while holding an rwlock will unlock the rwlock as it
* unwinds.
*/
struct rwlock {
/* priv */ order_lock: semaphore;
/* priv */ access_lock: sem<~[mut waitqueue]>;
/* priv */ state: Exclusive<rwlock_inner>;
}
/// Create a new rwlock, with one associated condvar.
fn rwlock() -> rwlock { rwlock_with_condvars(1) }
/**
* Create a new rwlock, with a specified number of associated condvars.
* Similar to mutex_with_condvars.
*/
fn rwlock_with_condvars(num_condvars: uint) -> rwlock {
rwlock { order_lock: semaphore(1),
access_lock: new_sem_and_signal(1, num_condvars),
state: exclusive(rwlock_inner { read_mode: false,
read_count: 0 }) }
}
impl &rwlock {
/// Create a new handle to the rwlock.
fn clone() -> rwlock {
rwlock { order_lock: (&(self.order_lock)).clone(),
access_lock: sem((*self.access_lock).clone()),
state: self.state.clone() }
}
/**
* Run a function with the rwlock in read mode. Calls to 'read' from other
* tasks may run concurrently with this one.
*/
fn read<U>(blk: fn() -> U) -> U {
let mut release = none;
unsafe {
do task::unkillable {
do (&self.order_lock).access {
let mut first_reader = false;
do self.state.with |state| {
first_reader = (state.read_count == 0);
state.read_count += 1;
}
if first_reader {
(&self.access_lock).acquire();
do self.state.with |state| {
// Must happen *after* getting access_lock. If
// this is set while readers are waiting, but
// while a writer holds the lock, the writer will
// be confused if they downgrade-then-unlock.
state.read_mode = true;
}
}
}
release = some(rwlock_release_read(self));
}
}
blk()
}
/**
* Run a function with the rwlock in write mode. No calls to 'read' or
* 'write' from other tasks will run concurrently with this one.
*/
fn write<U>(blk: fn() -> U) -> U {
unsafe {
do task::unkillable {
(&self.order_lock).acquire();
do (&self.access_lock).access {
(&self.order_lock).release();
task::rekillable(blk)
}
}
}
}
/**
* As write(), but also with a handle to a condvar. Waiting on this
* condvar will allow readers and writers alike to take the rwlock before
* the waiting task is signalled. (Note: a writer that waited and then
* was signalled might reacquire the lock before other waiting writers.)
*/
fn write_cond<U>(blk: fn(c: &condvar) -> U) -> U {
// NB: You might think I should thread the order_lock into the cond
// wait call, so that it gets waited on before access_lock gets
// reacquired upon being woken up. However, (a) this would be not
// pleasant to implement (and would mandate a new 'rw_cond' type) and
// (b) I think violating no-starvation in that case is appropriate.
unsafe {
do task::unkillable {
(&self.order_lock).acquire();
do (&self.access_lock).access_cond |cond| {
(&self.order_lock).release();
do task::rekillable { blk(cond) }
}
}
}
}
/**
* As write(), but with the ability to atomically 'downgrade' the lock;
* i.e., to become a reader without letting other writers get the lock in
* the meantime (such as unlocking and then re-locking as a reader would
* do). The block takes a "write mode token" argument, which can be
* transformed into a "read mode token" by calling downgrade(). Example:
* ~~~
* do lock.write_downgrade |write_mode| {
* do (&write_mode).write_cond |condvar| {
* ... exclusive access ...
* }
* let read_mode = lock.downgrade(write_mode);
* do (&read_mode).read {
* ... shared access ...
* }
* }
* ~~~
*/
fn write_downgrade<U>(blk: fn(+rwlock_write_mode) -> U) -> U {
// Implementation slightly different from the slicker 'write's above.
// The exit path is conditional on whether the caller downgrades.
let mut _release = none;
unsafe {
do task::unkillable {
(&self.order_lock).acquire();
(&self.access_lock).acquire();
(&self.order_lock).release();
}
_release = some(rwlock_release_downgrade(self));
}
blk(rwlock_write_mode { lock: self })
}
/// To be called inside of the write_downgrade block.
fn downgrade(+token: rwlock_write_mode) -> rwlock_read_mode {
if !ptr::ref_eq(self, token.lock) {
fail ~"Can't downgrade() with a different rwlock's write_mode!";
}
unsafe {
do task::unkillable {
let mut first_reader = false;
do self.state.with |state| {
assert !state.read_mode;
state.read_mode = true;
first_reader = (state.read_count == 0);
state.read_count += 1;
}
if !first_reader {
// Guaranteed not to let another writer in, because
// another reader was holding the order_lock. Hence they
// must be the one to get the access_lock (because all
// access_locks are acquired with order_lock held).
(&self.access_lock).release();
}
}
}
rwlock_read_mode { lock: token.lock }
}
}
// FIXME(#3136) should go inside of read()
#[doc(hidden)]
struct rwlock_release_read {
lock: &rwlock;
new(lock: &rwlock) { self.lock = lock; }
drop unsafe {
do task::unkillable {
let mut last_reader = false;
do self.lock.state.with |state| {
assert state.read_mode;
assert state.read_count > 0;
state.read_count -= 1;
if state.read_count == 0 {
last_reader = true;
state.read_mode = false;
}
}
if last_reader {
(&self.lock.access_lock).release();
}
}
}
}
// FIXME(#3136) should go inside of downgrade()
#[doc(hidden)]
struct rwlock_release_downgrade {
lock: &rwlock;
new(lock: &rwlock) { self.lock = lock; }
drop unsafe {
do task::unkillable {
let mut writer_or_last_reader = false;
do self.lock.state.with |state| {
if state.read_mode {
assert state.read_count > 0;
state.read_count -= 1;
if state.read_count == 0 {
// Case 1: Writer downgraded & was the last reader
writer_or_last_reader = true;
state.read_mode = false;
} else {
// Case 2: Writer downgraded & was not the last reader
}
} else {
// Case 3: Writer did not downgrade
writer_or_last_reader = true;
}
}
if writer_or_last_reader {
(&self.lock.access_lock).release();
}
}
}
}
/// The "write permission" token used for rwlock.write_downgrade().
struct rwlock_write_mode { /* priv */ lock: &rwlock; drop { } }
/// The "read permission" token used for rwlock.write_downgrade().
struct rwlock_read_mode { priv lock: &rwlock; drop { } }
impl &rwlock_write_mode {
/// Access the pre-downgrade rwlock in write mode.
fn write<U>(blk: fn() -> U) -> U { blk() }
/// Access the pre-downgrade rwlock in write mode with a condvar.
fn write_cond<U>(blk: fn(c: &condvar) -> U) -> U {
blk(&condvar { sem: &self.lock.access_lock })
}
}
impl &rwlock_read_mode {
/// Access the post-downgrade rwlock in read mode.
fn read<U>(blk: fn() -> U) -> U { blk() }
}
/****************************************************************************
* Tests
****************************************************************************/
#[cfg(test)]
mod tests {
/************************************************************************
* Semaphore tests
************************************************************************/
#[test]
fn test_sem_acquire_release() {
let s = ~semaphore(1);
s.acquire();
s.release();
s.acquire();
}
#[test]
fn test_sem_basic() {
let s = ~semaphore(1);
do s.access { }
}
#[test]
fn test_sem_as_mutex() {
let s = ~semaphore(1);
let s2 = ~s.clone();
do task::spawn {
do s2.access {
for 5.times { task::yield(); }
}
}
do s.access {
for 5.times { task::yield(); }
}
}
#[test]
fn test_sem_as_cvar() {
/* Child waits and parent signals */
let (c,p) = pipes::stream();
let s = ~semaphore(0);
let s2 = ~s.clone();
do task::spawn {
s2.acquire();
c.send(());
}
for 5.times { task::yield(); }
s.release();
let _ = p.recv();
/* Parent waits and child signals */
let (c,p) = pipes::stream();
let s = ~semaphore(0);
let s2 = ~s.clone();
do task::spawn {
for 5.times { task::yield(); }
s2.release();
let _ = p.recv();
}
s.acquire();
c.send(());
}
#[test]
fn test_sem_multi_resource() {
// Parent and child both get in the critical section at the same
// time, and shake hands.
let s = ~semaphore(2);
let s2 = ~s.clone();
let (c1,p1) = pipes::stream();
let (c2,p2) = pipes::stream();
do task::spawn {
do s2.access {
let _ = p2.recv();
c1.send(());
}
}
do s.access {
c2.send(());
let _ = p1.recv();
}
}
#[test]
fn test_sem_runtime_friendly_blocking() {
// Force the runtime to schedule two threads on the same sched_loop.
// When one blocks, it should schedule the other one.
do task::spawn_sched(task::manual_threads(1)) {
let s = ~semaphore(1);
let s2 = ~s.clone();
let (c,p) = pipes::stream();
let child_data = ~mut some((s2,c));
do s.access {
let (s2,c) = option::swap_unwrap(child_data);
do task::spawn {
c.send(());
do s2.access { }
c.send(());
}
let _ = p.recv(); // wait for child to come alive
for 5.times { task::yield(); } // let the child contend
}
let _ = p.recv(); // wait for child to be done
}
}
/************************************************************************
* Mutex tests
************************************************************************/
#[test]
fn test_mutex_lock() {
// Unsafely achieve shared state, and do the textbook
// "load tmp <- ptr; inc tmp; store ptr <- tmp" dance.
let (c,p) = pipes::stream();
let m = ~mutex();
let m2 = ~m.clone();
let sharedstate = ~0;
let ptr = ptr::addr_of(*sharedstate);
do task::spawn {
let sharedstate: &mut int =
unsafe { unsafe::reinterpret_cast(ptr) };
access_shared(sharedstate, m2, 10);
c.send(());
}
access_shared(sharedstate, m, 10);
let _ = p.recv();
assert *sharedstate == 20;
fn access_shared(sharedstate: &mut int, m: &mutex, n: uint) {
for n.times {
do m.lock {
let oldval = *sharedstate;
task::yield();
*sharedstate = oldval + 1;
}
}
}
}
#[test]
fn test_mutex_cond_wait() {
let m = ~mutex();
// Child wakes up parent
do m.lock_cond |cond| {
let m2 = ~m.clone();
do task::spawn {
do m2.lock_cond |cond| {
let woken = cond.signal();
assert woken;
}
}
cond.wait();
}
// Parent wakes up child
let (chan,port) = pipes::stream();
let m3 = ~m.clone();
do task::spawn {
do m3.lock_cond |cond| {
chan.send(());
cond.wait();
chan.send(());
}
}
let _ = port.recv(); // Wait until child gets in the mutex
do m.lock_cond |cond| {
let woken = cond.signal();
assert woken;
}
let _ = port.recv(); // Wait until child wakes up
}
#[cfg(test)]
fn test_mutex_cond_broadcast_helper(num_waiters: uint) {
let m = ~mutex();
let mut ports = ~[];
for num_waiters.times {
let mi = ~m.clone();
let (chan, port) = pipes::stream();
vec::push(ports, port);
do task::spawn {
do mi.lock_cond |cond| {
chan.send(());
cond.wait();
chan.send(());
}
}
}
// wait until all children get in the mutex
for ports.each |port| { let _ = port.recv(); }
do m.lock_cond |cond| {
let num_woken = cond.broadcast();
assert num_woken == num_waiters;
}
// wait until all children wake up
for ports.each |port| { let _ = port.recv(); }
}
#[test]
fn test_mutex_cond_broadcast() {
test_mutex_cond_broadcast_helper(12);
}
#[test]
fn test_mutex_cond_broadcast_none() {
test_mutex_cond_broadcast_helper(0);
}
#[test]
fn test_mutex_cond_no_waiter() {
let m = ~mutex();
let m2 = ~m.clone();
do task::try {
do m.lock_cond |_x| { }
};
do m2.lock_cond |cond| {
assert !cond.signal();
}
}
#[test] #[ignore(cfg(windows))]
fn test_mutex_killed_simple() {
// Mutex must get automatically unlocked if failed/killed within.
let m = ~mutex();
let m2 = ~m.clone();
let result: result::result<(),()> = do task::try {
do m2.lock {
fail;
}
};
assert result.is_err();
// child task must have finished by the time try returns
do m.lock { }
}
#[test] #[ignore(cfg(windows))]
fn test_mutex_killed_cond() {
// Getting killed during cond wait must not corrupt the mutex while
// unwinding (e.g. double unlock).
let m = ~mutex();
let m2 = ~m.clone();
let result: result::result<(),()> = do task::try {
let (c,p) = pipes::stream();
do task::spawn { // linked
let _ = p.recv(); // wait for sibling to get in the mutex
task::yield();
fail;
}
do m2.lock_cond |cond| {
c.send(()); // tell sibling go ahead
cond.wait(); // block forever
}
};
assert result.is_err();
// child task must have finished by the time try returns
do m.lock_cond |cond| {
let woken = cond.signal();
assert !woken;
}
}
#[test] #[ignore(cfg(windows))]
fn test_mutex_killed_broadcast() {
let m = ~mutex();
let m2 = ~m.clone();
let (c,p) = pipes::stream();
let result: result::result<(),()> = do task::try {
let mut sibling_convos = ~[];
for 2.times {
let (c,p) = pipes::stream();
let c = ~mut some(c);
vec::push(sibling_convos, p);
let mi = ~m2.clone();
// spawn sibling task
do task::spawn { // linked
do mi.lock_cond |cond| {
let c = option::swap_unwrap(c);
c.send(()); // tell sibling to go ahead
let _z = send_on_failure(c);
cond.wait(); // block forever
}
}
}
for vec::each(sibling_convos) |p| {
let _ = p.recv(); // wait for sibling to get in the mutex
}
do m2.lock { }
c.send(sibling_convos); // let parent wait on all children
fail;
};
assert result.is_err();
// child task must have finished by the time try returns
for vec::each(p.recv()) |p| { p.recv(); } // wait on all its siblings
do m.lock_cond |cond| {
let woken = cond.broadcast();
assert woken == 0;
}
struct send_on_failure {
c: pipes::chan<()>;
new(+c: pipes::chan<()>) { self.c = c; }
drop { self.c.send(()); }
}
}
#[test]
fn test_mutex_cond_signal_on_0() {
// Tests that signal_on(0) is equivalent to signal().
let m = ~mutex();
do m.lock_cond |cond| {
let m2 = ~m.clone();
do task::spawn {
do m2.lock_cond |cond| {
cond.signal_on(0);
}
}
cond.wait();
}
}
#[test] #[ignore(cfg(windows))]
fn test_mutex_different_conds() {
let result = do task::try {
let m = ~mutex_with_condvars(2);
let m2 = ~m.clone();
let (c,p) = pipes::stream();
do task::spawn {
do m2.lock_cond |cond| {
c.send(());
cond.wait_on(1);
}
}
let _ = p.recv();
do m.lock_cond |cond| {
if !cond.signal_on(0) {
fail; // success; punt sibling awake.
}
}
};
assert result.is_err();
}
#[test] #[ignore(cfg(windows))]
fn test_mutex_no_condvars() {
let result = do task::try {
let m = ~mutex_with_condvars(0);
do m.lock_cond |cond| { cond.wait(); }
};
assert result.is_err();
let result = do task::try {
let m = ~mutex_with_condvars(0);
do m.lock_cond |cond| { cond.signal(); }
};
assert result.is_err();
let result = do task::try {
let m = ~mutex_with_condvars(0);
do m.lock_cond |cond| { cond.broadcast(); }
};
assert result.is_err();
}
/************************************************************************
* Reader/writer lock tests
************************************************************************/
#[cfg(test)]
enum rwlock_mode { read, write, downgrade, downgrade_read }
#[cfg(test)]
fn lock_rwlock_in_mode(x: &rwlock, mode: rwlock_mode, blk: fn()) {
match mode {
read => x.read(blk),
write => x.write(blk),
downgrade =>
do x.write_downgrade |mode| {
// FIXME(#2282)
let mode = unsafe { unsafe::transmute_region(&mode) };
mode.write(blk);
},
downgrade_read =>
do x.write_downgrade |mode| {
let mode = x.downgrade(mode);
// FIXME(#2282)
let mode = unsafe { unsafe::transmute_region(&mode) };
mode.read(blk);
},
}
}
#[cfg(test)]
fn test_rwlock_exclusion(+x: ~rwlock, mode1: rwlock_mode,
mode2: rwlock_mode) {
// Test mutual exclusion between readers and writers. Just like the
// mutex mutual exclusion test, a ways above.
let (c,p) = pipes::stream();
let x2 = ~x.clone();
let sharedstate = ~0;
let ptr = ptr::addr_of(*sharedstate);
do task::spawn {
let sharedstate: &mut int =
unsafe { unsafe::reinterpret_cast(ptr) };
access_shared(sharedstate, x2, mode1, 10);
c.send(());
}
access_shared(sharedstate, x, mode2, 10);
let _ = p.recv();
assert *sharedstate == 20;
fn access_shared(sharedstate: &mut int, x: &rwlock, mode: rwlock_mode,
n: uint) {
for n.times {
do lock_rwlock_in_mode(x, mode) {
let oldval = *sharedstate;
task::yield();
*sharedstate = oldval + 1;
}
}
}
}
#[test]
fn test_rwlock_readers_wont_modify_the_data() {
test_rwlock_exclusion(~rwlock(), read, write);
test_rwlock_exclusion(~rwlock(), write, read);
test_rwlock_exclusion(~rwlock(), read, downgrade);
test_rwlock_exclusion(~rwlock(), downgrade, read);
}
#[test]
fn test_rwlock_writers_and_writers() {
test_rwlock_exclusion(~rwlock(), write, write);
test_rwlock_exclusion(~rwlock(), write, downgrade);
test_rwlock_exclusion(~rwlock(), downgrade, write);
test_rwlock_exclusion(~rwlock(), downgrade, downgrade);
}
#[cfg(test)]
fn test_rwlock_handshake(+x: ~rwlock, mode1: rwlock_mode,
mode2: rwlock_mode, make_mode2_go_first: bool) {
// Much like sem_multi_resource.
let x2 = ~x.clone();
let (c1,p1) = pipes::stream();
let (c2,p2) = pipes::stream();
do task::spawn {
if !make_mode2_go_first {
let _ = p2.recv(); // parent sends to us once it locks, or ...
}
do lock_rwlock_in_mode(x2, mode2) {
if make_mode2_go_first {
c1.send(()); // ... we send to it once we lock
}
let _ = p2.recv();
c1.send(());
}
}
if make_mode2_go_first {
let _ = p1.recv(); // child sends to us once it locks, or ...
}
do lock_rwlock_in_mode(x, mode1) {
if !make_mode2_go_first {
c2.send(()); // ... we send to it once we lock
}
c2.send(());
let _ = p1.recv();
}
}
#[test]
fn test_rwlock_readers_and_readers() {
test_rwlock_handshake(~rwlock(), read, read, false);
// The downgrader needs to get in before the reader gets in, otherwise
// they cannot end up reading at the same time.
test_rwlock_handshake(~rwlock(), downgrade_read, read, false);
test_rwlock_handshake(~rwlock(), read, downgrade_read, true);
// Two downgrade_reads can never both end up reading at the same time.
}
#[test]
fn test_rwlock_downgrade_unlock() {
// Tests that downgrade can unlock the lock in both modes
let x = ~rwlock();
do lock_rwlock_in_mode(x, downgrade) { }
test_rwlock_handshake(x, read, read, false);
let y = ~rwlock();
do lock_rwlock_in_mode(y, downgrade_read) { }
test_rwlock_exclusion(y, write, write);
}
#[test]
fn test_rwlock_read_recursive() {
let x = ~rwlock();
do x.read { do x.read { } }
}
#[test]
fn test_rwlock_cond_wait() {
// As test_mutex_cond_wait above.
let x = ~rwlock();
// Child wakes up parent
do x.write_cond |cond| {
let x2 = ~x.clone();
do task::spawn {
do x2.write_cond |cond| {
let woken = cond.signal();
assert woken;
}
}
cond.wait();
}
// Parent wakes up child
let (chan,port) = pipes::stream();
let x3 = ~x.clone();
do task::spawn {
do x3.write_cond |cond| {
chan.send(());
cond.wait();
chan.send(());
}
}
let _ = port.recv(); // Wait until child gets in the rwlock
do x.read { } // Must be able to get in as a reader in the meantime
do x.write_cond |cond| { // Or as another writer
let woken = cond.signal();
assert woken;
}
let _ = port.recv(); // Wait until child wakes up
do x.read { } // Just for good measure
}
#[cfg(test)]
fn test_rwlock_cond_broadcast_helper(num_waiters: uint, dg1: bool,
dg2: bool) {
// Much like the mutex broadcast test. Downgrade-enabled.
fn lock_cond(x: &rwlock, downgrade: bool, blk: fn(c: &condvar)) {
if downgrade {
do x.write_downgrade |mode| {
// FIXME(#2282)
let mode = unsafe { unsafe::transmute_region(&mode) };
mode.write_cond(blk)
}
} else {
x.write_cond(blk)
}
}
let x = ~rwlock();
let mut ports = ~[];
for num_waiters.times {
let xi = ~x.clone();
let (chan, port) = pipes::stream();
vec::push(ports, port);
do task::spawn {
do lock_cond(xi, dg1) |cond| {
chan.send(());
cond.wait();
chan.send(());
}
}
}
// wait until all children get in the mutex
for ports.each |port| { let _ = port.recv(); }
do lock_cond(x, dg2) |cond| {
let num_woken = cond.broadcast();
assert num_woken == num_waiters;
}
// wait until all children wake up
for ports.each |port| { let _ = port.recv(); }
}
#[test]
fn test_rwlock_cond_broadcast() {
test_rwlock_cond_broadcast_helper(0, true, true);
test_rwlock_cond_broadcast_helper(0, true, false);
test_rwlock_cond_broadcast_helper(0, false, true);
test_rwlock_cond_broadcast_helper(0, false, false);
test_rwlock_cond_broadcast_helper(12, true, true);
test_rwlock_cond_broadcast_helper(12, true, false);
test_rwlock_cond_broadcast_helper(12, false, true);
test_rwlock_cond_broadcast_helper(12, false, false);
}
#[cfg(test)] #[ignore(cfg(windows))]
fn rwlock_kill_helper(mode1: rwlock_mode, mode2: rwlock_mode) {
// Mutex must get automatically unlocked if failed/killed within.
let x = ~rwlock();
let x2 = ~x.clone();
let result: result::result<(),()> = do task::try {
do lock_rwlock_in_mode(x2, mode1) {
fail;
}
};
assert result.is_err();
// child task must have finished by the time try returns
do lock_rwlock_in_mode(x, mode2) { }
}
#[test] #[ignore(cfg(windows))]
fn test_rwlock_reader_killed_writer() { rwlock_kill_helper(read, write); }
#[test] #[ignore(cfg(windows))]
fn test_rwlock_writer_killed_reader() { rwlock_kill_helper(write,read ); }
#[test] #[ignore(cfg(windows))]
fn test_rwlock_reader_killed_reader() { rwlock_kill_helper(read, read ); }
#[test] #[ignore(cfg(windows))]
fn test_rwlock_writer_killed_writer() { rwlock_kill_helper(write,write); }
#[test] #[ignore(cfg(windows))]
fn test_rwlock_kill_downgrader() {
rwlock_kill_helper(downgrade, read);
rwlock_kill_helper(read, downgrade);
rwlock_kill_helper(downgrade, write);
rwlock_kill_helper(write, downgrade);
rwlock_kill_helper(downgrade_read, read);
rwlock_kill_helper(read, downgrade_read);
rwlock_kill_helper(downgrade_read, write);
rwlock_kill_helper(write, downgrade_read);
rwlock_kill_helper(downgrade_read, downgrade);
rwlock_kill_helper(downgrade_read, downgrade);
rwlock_kill_helper(downgrade, downgrade_read);
rwlock_kill_helper(downgrade, downgrade_read);
}
#[test] #[should_fail] #[ignore(cfg(windows))]
fn test_rwlock_downgrade_cant_swap() {
// Tests that you can't downgrade with a different rwlock's token.
let x = ~rwlock();
let y = ~rwlock();
do x.write_downgrade |xwrite| {
let mut xopt = some(xwrite);
do y.write_downgrade |_ywrite| {
y.downgrade(option::swap_unwrap(&mut xopt));
error!("oops, y.downgrade(x) should have failed!");
}
}
}
}