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Synthesize a flush_chan upcall right before a channel's ref_count drops to zero. This should only happen in the Rust code and not in the drop glue, or on the unwind path. This change allows the task owning the channel to block on a flush and delete its own channel. This change also cleans up some code around rust_port and rust_chan.

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This commit is contained in:
Michael Bebenita
2010-08-09 08:15:34 -07:00
parent 5917ca3519
commit 97d6342bf0
9 changed files with 113 additions and 55 deletions
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68
src/rt/rust_upcall.cpp
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@@ -98,26 +98,50 @@ upcall_new_chan(rust_task *task, rust_port *port) {
}
/**
* Called whenever the channel's ref count drops to zero.
* Called whenever this channel needs to be flushed. This can happen due to a
* flush statement, or automatically whenever a channel's ref count is
* about to drop to zero.
*/
extern "C" CDECL void upcall_del_chan(rust_task *task, rust_chan *chan) {
extern "C" CDECL void
upcall_flush_chan(rust_task *task, rust_chan *chan) {
LOG_UPCALL_ENTRY(task);
rust_dom *dom = task->dom;
task->log(rust_log::UPCALL | rust_log::MEM | rust_log::COMM,
"upcall del_chan(0x%" PRIxPTR ")", (uintptr_t) chan);
I(dom, !chan->ref_count);
task->log(rust_log::UPCALL | rust_log::COMM,
"flush chan: 0x%" PRIxPTR, chan);
if (!chan->buffer.is_empty() && chan->is_associated()) {
A(dom, !chan->port->is_proxy(),
"Channels to remote ports should be flushed automatically.");
// A target port may still be reading from this channel.
// Block on this channel until it has been completely drained
// by the port.
task->block(chan);
task->yield(2);
if (chan->buffer.is_empty()) {
return;
}
A(dom, chan->port->is_proxy() == false,
"Channels to remote ports should be flushed automatically.");
// Block on the port until this channel has been completely drained
// by the port.
task->block(chan->port);
task->yield(2);
}
/**
* Called whenever the channel's ref count drops to zero.
*
* Cannot Yield: If the task were to unwind, the dropped ref would still
* appear to be live, causing modify-after-free errors.
*/
extern "C" CDECL void upcall_del_chan(rust_task *task, rust_chan *chan) {
LOG_UPCALL_ENTRY(task);
task->log(rust_log::UPCALL | rust_log::MEM | rust_log::COMM,
"upcall del_chan(0x%" PRIxPTR ")", (uintptr_t) chan);
A(task->dom, chan->ref_count == 0,
"Channel's ref count should be zero.");
if (chan->is_associated()) {
A(task->dom, chan->buffer.is_empty(),
"Channel's buffer should be empty.");
chan->disassociate();
}
delete chan;
}
@@ -183,8 +207,7 @@ upcall_send(rust_task *task, rust_chan *chan, void *sptr) {
"chan: 0x%" PRIxPTR ", sptr: 0x%" PRIxPTR ", size: %d",
(uintptr_t) chan, (uintptr_t) sptr,
chan->port->delegate()->unit_sz);
chan->buffer.enqueue(sptr);
chan->transmit();
chan->send(sptr);
task->log(rust_log::COMM, "=== sent data ===>");
}
@@ -197,17 +220,8 @@ upcall_recv(rust_task *task, uintptr_t *dptr, rust_port *port) {
(uintptr_t) port, (uintptr_t) dptr, port->unit_sz,
port->chans.length());
for (uint32_t i = 0; i < port->chans.length(); i++) {
rust_chan *chan = port->chans[i];
if (chan->buffer.is_empty() == false) {
chan->buffer.dequeue(dptr);
if (chan->buffer.is_empty() && chan->task->blocked()) {
chan->task->wakeup(chan);
delete chan;
}
task->log(rust_log::COMM, "<=== read data ===");
return;
}
if (port->receive(dptr)) {
return;
}
// No data was buffered on any incoming channel, so block this task
@@ -260,6 +274,8 @@ upcall_exit(rust_task *task) {
LOG_UPCALL_ENTRY(task);
task->log(rust_log::UPCALL | rust_log::TASK,
"task ref_count: %d", task->ref_count);
A(task->dom, task->ref_count >= 0,
"Task ref_count should not be negative on exit!");
task->die();
task->notify_tasks_waiting_to_join();
task->yield(1);