summaryrefslogtreecommitdiff
path: root/src/pipe.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'src/pipe.cpp')
-rw-r--r--src/pipe.cpp420
1 files changed, 232 insertions, 188 deletions
diff --git a/src/pipe.cpp b/src/pipe.cpp
index 200beb0..a60e519 100644
--- a/src/pipe.cpp
+++ b/src/pipe.cpp
@@ -4,44 +4,68 @@
This file is part of 0MQ.
0MQ is free software; you can redistribute it and/or modify it under
- the terms of the Lesser GNU General Public License as published by
+ the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
0MQ is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- Lesser GNU General Public License for more details.
+ GNU Lesser General Public License for more details.
- You should have received a copy of the Lesser GNU General Public License
+ You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <new>
+
#include "../include/zmq.h"
#include "pipe.hpp"
+#include "likely.hpp"
-zmq::reader_t::reader_t (object_t *parent_, uint64_t lwm_) :
+zmq::reader_t::reader_t (object_t *parent_, pipe_t *pipe_,
+ uint64_t lwm_) :
object_t (parent_),
- pipe (NULL),
- peer (NULL),
+ active (true),
+ pipe (pipe_),
+ writer (NULL),
lwm (lwm_),
msgs_read (0),
- endpoint (NULL)
-{}
+ sink (NULL),
+ terminating (false)
+{
+ // Note that writer is not set here. Writer will inform reader about its
+ // address once it is created (via set_writer method).
+}
+
+void zmq::reader_t::set_writer (writer_t *writer_)
+{
+ zmq_assert (!writer);
+ writer = writer_;
+}
zmq::reader_t::~reader_t ()
{
- if (pipe)
- unregister_pipe (pipe);
+ // Pipe as such is owned and deallocated by reader object.
+ // The point is that reader processes the last step of terminal
+ // handshaking (term_ack).
+ zmq_assert (pipe);
+
+ // First delete all the unread messages in the pipe. We have to do it by
+ // hand because zmq_msg_t is a POD, not a class, so there's no associated
+ // destructor.
+ zmq_msg_t msg;
+ while (pipe->read (&msg))
+ zmq_msg_close (&msg);
+
+ delete pipe;
}
-void zmq::reader_t::set_pipe (pipe_t *pipe_)
+void zmq::reader_t::set_event_sink (i_reader_events *sink_)
{
- zmq_assert (!pipe);
- pipe = pipe_;
- peer = &pipe->writer;
- register_pipe (pipe);
+ zmq_assert (!sink);
+ sink = sink_;
}
bool zmq::reader_t::is_delimiter (zmq_msg_t &msg_)
@@ -53,19 +77,24 @@ bool zmq::reader_t::is_delimiter (zmq_msg_t &msg_)
bool zmq::reader_t::check_read ()
{
+ if (!active)
+ return false;
+
// Check if there's an item in the pipe.
- // If not, deactivate the pipe.
if (!pipe->check_read ()) {
- endpoint->kill (this);
+ active = false;
return false;
}
// If the next item in the pipe is message delimiter,
// initiate its termination.
if (pipe->probe (is_delimiter)) {
- if (endpoint)
- endpoint->detach_inpipe (this);
- term ();
+ zmq_msg_t msg;
+ bool ok = pipe->read (&msg);
+ zmq_assert (ok);
+ if (sink)
+ sink->delimited (this);
+ terminate ();
return false;
}
@@ -74,17 +103,20 @@ bool zmq::reader_t::check_read ()
bool zmq::reader_t::read (zmq_msg_t *msg_)
{
+ if (!active)
+ return false;
+
if (!pipe->read (msg_)) {
- endpoint->kill (this);
+ active = false;
return false;
}
// If delimiter was read, start termination process of the pipe.
unsigned char *offset = 0;
if (msg_->content == (void*) (offset + ZMQ_DELIMITER)) {
- if (endpoint)
- endpoint->detach_inpipe (this);
- term ();
+ if (sink)
+ sink->delimited (this);
+ terminate ();
return false;
}
@@ -92,87 +124,104 @@ bool zmq::reader_t::read (zmq_msg_t *msg_)
msgs_read++;
if (lwm > 0 && msgs_read % lwm == 0)
- send_reader_info (peer, msgs_read);
+ send_activate_writer (writer, msgs_read);
return true;
}
-void zmq::reader_t::set_endpoint (i_endpoint *endpoint_)
+void zmq::reader_t::terminate ()
{
- endpoint = endpoint_;
-}
+ // If termination was already started by the peer, do nothing.
+ if (terminating)
+ return;
-void zmq::reader_t::term ()
-{
- endpoint = NULL;
- send_pipe_term (peer);
+ active = false;
+ terminating = true;
+ send_pipe_term (writer);
}
-void zmq::reader_t::process_revive ()
+void zmq::reader_t::process_activate_reader ()
{
- // Beacuse of command throttling mechanism, incoming termination request
- // may not have been processed before subsequent send.
- // In that case endpoint is NULL.
- if (endpoint)
- endpoint->revive (this);
+ // Forward the event to the sink (either socket or session).
+ active = true;
+ sink->activated (this);
}
void zmq::reader_t::process_pipe_term_ack ()
{
- peer = NULL;
- delete pipe;
+ // At this point writer may already be deallocated.
+ // For safety's sake drop the reference to it.
+ writer = NULL;
+
+ // Notify owner about the termination.
+ zmq_assert (sink);
+ sink->terminated (this);
+
+ // Deallocate resources.
+ delete this;
}
-zmq::writer_t::writer_t (object_t *parent_,
+zmq::writer_t::writer_t (object_t *parent_, pipe_t *pipe_, reader_t *reader_,
uint64_t hwm_, int64_t swap_size_) :
object_t (parent_),
- pipe (NULL),
- peer (NULL),
+ active (true),
+ pipe (pipe_),
+ reader (reader_),
hwm (hwm_),
msgs_read (0),
msgs_written (0),
- msg_store (NULL),
- extra_msg_flag (false),
- stalled (false),
- pending_close (false),
- endpoint (NULL)
+ swap (NULL),
+ sink (NULL),
+ swapping (false),
+ pending_delimiter (false),
+ terminating (false)
{
+ // Inform reader about the writer.
+ reader->set_writer (this);
+
+ // Open the swap file, if required.
if (swap_size_ > 0) {
- msg_store = new (std::nothrow) msg_store_t (swap_size_);
- if (msg_store != NULL) {
- if (msg_store->init () < 0) {
- delete msg_store;
- msg_store = NULL;
- }
- }
+ swap = new (std::nothrow) swap_t (swap_size_);
+ zmq_assert (swap);
+ int rc = swap->init ();
+ zmq_assert (rc == 0);
}
}
-void zmq::writer_t::set_endpoint (i_endpoint *endpoint_)
-{
- endpoint = endpoint_;
-}
-
zmq::writer_t::~writer_t ()
{
- if (extra_msg_flag)
- zmq_msg_close (&extra_msg);
-
- delete msg_store;
+ if (swap)
+ delete swap;
}
-void zmq::writer_t::set_pipe (pipe_t *pipe_)
+void zmq::writer_t::set_event_sink (i_writer_events *sink_)
{
- zmq_assert (!pipe);
- pipe = pipe_;
- peer = &pipe->reader;
+ zmq_assert (!sink);
+ sink = sink_;
}
bool zmq::writer_t::check_write ()
{
- if (pipe_full () && (msg_store == NULL || msg_store->full () || extra_msg_flag)) {
- stalled = true;
+ // We've already checked and there's no space free for the new message.
+ // There's no point in checking once again.
+ if (unlikely (!active))
return false;
+
+ if (unlikely (swapping)) {
+ if (unlikely (swap->full ())) {
+ active = false;
+ return false;
+ }
+ }
+ else {
+ if (unlikely (pipe_full ())) {
+ if (swap)
+ swapping = true;
+ else {
+ active = false;
+ return false;
+ }
+ }
}
return true;
@@ -180,73 +229,67 @@ bool zmq::writer_t::check_write ()
bool zmq::writer_t::write (zmq_msg_t *msg_)
{
- if (!check_write ())
+ if (unlikely (!check_write ()))
return false;
- if (pipe_full ()) {
- if (msg_store->store (msg_)) {
- if (!(msg_->flags & ZMQ_MSG_MORE))
- msg_store->commit ();
- } else {
- extra_msg = *msg_;
- extra_msg_flag = true;
- }
- }
- else {
- pipe->write (*msg_, msg_->flags & ZMQ_MSG_MORE);
+ if (unlikely (swapping)) {
+ bool stored = swap->store (msg_);
+ zmq_assert (stored);
if (!(msg_->flags & ZMQ_MSG_MORE))
- msgs_written++;
+ swap->commit ();
+ return true;
}
+ pipe->write (*msg_, msg_->flags & ZMQ_MSG_MORE);
+ if (!(msg_->flags & ZMQ_MSG_MORE))
+ msgs_written++;
+
return true;
}
void zmq::writer_t::rollback ()
{
- if (extra_msg_flag && extra_msg.flags & ZMQ_MSG_MORE) {
- zmq_msg_close (&extra_msg);
- extra_msg_flag = false;
+ // Remove incomplete message from the swap.
+ if (unlikely (swapping)) {
+ swap->rollback ();
+ return;
}
- if (msg_store != NULL)
- msg_store->rollback ();
-
+ // Remove incomplete message from the pipe.
zmq_msg_t msg;
- // Remove all incomplete messages from the pipe.
while (pipe->unwrite (&msg)) {
zmq_assert (msg.flags & ZMQ_MSG_MORE);
zmq_msg_close (&msg);
}
-
- if (stalled && endpoint != NULL && check_write ()) {
- stalled = false;
- endpoint->revive (this);
- }
}
void zmq::writer_t::flush ()
{
- if (!pipe->flush ())
- send_revive (peer);
+ // In the swapping mode, flushing is automatically handled by swap object.
+ if (!swapping && !pipe->flush ())
+ send_activate_reader (reader);
}
-void zmq::writer_t::term ()
+void zmq::writer_t::terminate ()
{
- endpoint = NULL;
+ // Prevent double termination.
+ if (terminating)
+ return;
+
+ // Mark the pipe as not available for writing.
+ active = false;
// Rollback any unfinished messages.
rollback ();
- if (msg_store == NULL || (msg_store->empty () && !extra_msg_flag))
- write_delimiter ();
- else
- pending_close = true;
-}
+ if (swapping) {
+ pending_delimiter = true;
+ return;
+ }
-void zmq::writer_t::write_delimiter ()
-{
- // Push delimiter into the pipe.
- // Trick the compiler to belive that the tag is a valid pointer.
+ // Push delimiter into the pipe. Trick the compiler to belive that
+ // the tag is a valid pointer. Note that watermarks are not checked
+ // thus the delimiter can be written even though the pipe is full.
zmq_msg_t msg;
const unsigned char *offset = 0;
msg.content = (void*) (offset + ZMQ_DELIMITER);
@@ -255,109 +298,110 @@ void zmq::writer_t::write_delimiter ()
flush ();
}
-void zmq::writer_t::process_reader_info (uint64_t msgs_read_)
+void zmq::writer_t::process_activate_writer (uint64_t msgs_read_)
{
- zmq_msg_t msg;
-
+ // Store the reader's message sequence number.
msgs_read = msgs_read_;
- if (msg_store) {
- // Move messages from backing store into pipe.
- while (!pipe_full () && !msg_store->empty ()) {
- msg_store->fetch(&msg);
- // Write message into the pipe.
+ // If we are in the swapping mode, we have some messages in the swap.
+ // Given that pipe is now ready for writing we can move part of the
+ // swap into the pipe.
+ if (swapping) {
+ zmq_msg_t msg;
+ while (!pipe_full () && !swap->empty ()) {
+ swap->fetch(&msg);
pipe->write (msg, msg.flags & ZMQ_MSG_MORE);
if (!(msg.flags & ZMQ_MSG_MORE))
msgs_written++;
}
-
- if (extra_msg_flag) {
- if (!pipe_full ()) {
- pipe->write (extra_msg, extra_msg.flags & ZMQ_MSG_MORE);
- if (!(extra_msg.flags & ZMQ_MSG_MORE))
- msgs_written++;
- extra_msg_flag = false;
- }
- else if (msg_store->store (&extra_msg)) {
- if (!(extra_msg.flags & ZMQ_MSG_MORE))
- msg_store->commit ();
- extra_msg_flag = false;
+ if (!pipe->flush ())
+ send_activate_reader (reader);
+
+ // There are no more messages in the swap. We can switch into
+ // standard in-memory mode.
+ if (swap->empty ()) {
+ swapping = false;
+
+ // Push delimiter into the pipe. Trick the compiler to belive that
+ // the tag is a valid pointer. Note that watermarks are not checked
+ // thus the delimiter can be written even though the pipe is full.
+ if (pending_delimiter) {
+ zmq_msg_t msg;
+ const unsigned char *offset = 0;
+ msg.content = (void*) (offset + ZMQ_DELIMITER);
+ msg.flags = 0;
+ pipe->write (msg, false);
+ flush ();
+ return;
}
}
-
- if (pending_close && msg_store->empty () && !extra_msg_flag) {
- write_delimiter ();
- pending_close = false;
- }
-
- flush ();
}
- if (stalled && endpoint != NULL) {
- stalled = false;
- endpoint->revive (this);
+ // If the writer was non-active before, let's make it active
+ // (available for writing messages to).
+ if (!active) {
+ active = true;
+ zmq_assert (sink);
+ sink->activated (this);
}
}
void zmq::writer_t::process_pipe_term ()
{
- if (endpoint)
- endpoint->detach_outpipe (this);
+ send_pipe_term_ack (reader);
- reader_t *p = peer;
- peer = NULL;
- send_pipe_term_ack (p);
-}
+ // The above command allows reader to deallocate itself and the pipe.
+ // For safety's sake we'll drop the pointers here.
+ reader = NULL;
+ pipe = NULL;
-bool zmq::writer_t::pipe_full ()
-{
- return hwm > 0 && msgs_written - msgs_read == hwm;
-}
+ // Notify owner about the termination.
+ zmq_assert (sink);
+ sink->terminated (this);
-zmq::pipe_t::pipe_t (object_t *reader_parent_, object_t *writer_parent_,
- uint64_t hwm_, int64_t swap_size_) :
- reader (reader_parent_, compute_lwm (hwm_)),
- writer (writer_parent_, hwm_, swap_size_)
-{
- reader.set_pipe (this);
- writer.set_pipe (this);
+ // Deallocate the resources.
+ delete this;
}
-zmq::pipe_t::~pipe_t ()
+bool zmq::writer_t::pipe_full ()
{
- // Deallocate all the unread messages in the pipe. We have to do it by
- // hand because zmq_msg_t is a POD, not a class, so there's no associated
- // destructor.
- zmq_msg_t msg;
- while (read (&msg))
- zmq_msg_close (&msg);
+ return hwm > 0 && msgs_written - msgs_read == hwm;
}
-uint64_t zmq::pipe_t::compute_lwm (uint64_t hwm_)
+void zmq::create_pipe (object_t *reader_parent_, object_t *writer_parent_,
+ uint64_t hwm_, int64_t swap_size_, reader_t **reader_, writer_t **writer_)
{
- // Following point should be taken into consideration when computing
- // low watermark:
- //
- // 1. LWM has to be less than HWM.
- // 2. LWM cannot be set to very low value (such as zero) as after filling
- // the queue it would start to refill only after all the messages are
- // read from it and thus unnecessarily hold the progress back.
- // 3. LWM cannot be set to very high value (such as HWM-1) as it would
- // result in lock-step filling of the queue - if a single message is read
- // from a full queue, writer thread is resumed to write exactly one
- // message to the queue and go back to sleep immediately. This would
- // result in low performance.
- //
- // Given the 3. it would be good to keep HWM and LWM as far apart as
- // possible to reduce the thread switching overhead to almost zero,
- // say HWM-LWM should be 500 (max_wm_delta).
- //
- // That done, we still we have to account for the cases where HWM<500 thus
- // driving LWM to negative numbers. Let's make LWM 1/2 of HWM in such cases.
-
- if (hwm_ > max_wm_delta * 2)
- return hwm_ - max_wm_delta;
- else
- return (hwm_ + 1) / 2;
+ // First compute the low water mark. Following point should be taken
+ // into consideration:
+ //
+ // 1. LWM has to be less than HWM.
+ // 2. LWM cannot be set to very low value (such as zero) as after filling
+ // the queue it would start to refill only after all the messages are
+ // read from it and thus unnecessarily hold the progress back.
+ // 3. LWM cannot be set to very high value (such as HWM-1) as it would
+ // result in lock-step filling of the queue - if a single message is
+ // read from a full queue, writer thread is resumed to write exactly one
+ // message to the queue and go back to sleep immediately. This would
+ // result in low performance.
+ //
+ // Given the 3. it would be good to keep HWM and LWM as far apart as
+ // possible to reduce the thread switching overhead to almost zero,
+ // say HWM-LWM should be max_wm_delta.
+ //
+ // That done, we still we have to account for the cases where
+ // HWM < max_wm_delta thus driving LWM to negative numbers.
+ // Let's make LWM 1/2 of HWM in such cases.
+ uint64_t lwm = (hwm_ > max_wm_delta * 2) ?
+ hwm_ - max_wm_delta : (hwm_ + 1) / 2;
+
+ // Create all three objects pipe consists of: the pipe per se, reader and
+ // writer. The pipe will be handled by reader and writer, its never passed
+ // to the user. Reader and writer are returned to the user.
+ pipe_t *pipe = new (std::nothrow) pipe_t ();
+ zmq_assert (pipe);
+ *reader_ = new (std::nothrow) reader_t (reader_parent_, pipe, lwm);
+ zmq_assert (*reader_);
+ *writer_ = new (std::nothrow) writer_t (writer_parent_, pipe, *reader_,
+ hwm_, swap_size_);
+ zmq_assert (*writer_);
}
-