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Reworked zmq::proxy() for improved performance.

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This commit is contained in:
bjovke
2017-04-10 11:34:24 +02:00
parent 3e55545ab0
commit a7977a5e84
1 changed files with 278 additions and 0 deletions
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278
src/proxy.cpp
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@@ -52,6 +52,30 @@
#include "socket_base.hpp"
#include "err.hpp"
#ifdef ZMQ_HAVE_POLLER
#include "socket_poller.hpp"
// Macros for repetitive code.
// PROXY_CLEANUP() must not be used before these variables are initialized.
#define PROXY_CLEANUP()\
delete poller_all;\
delete poller_in;\
delete poller_control;\
delete poller_receive_blocked;\
delete poller_send_blocked;\
delete poller_both_blocked;\
#define CHECK_RC_EXIT_ON_FAILURE()\
if (rc < 0) {\
PROXY_CLEANUP();\
return close_and_return (&msg, -1);\
}
#endif // ZMQ_HAVE_POLLER
int capture (
class zmq::socket_base_t *capture_,
zmq::msg_t& msg_,
@@ -105,6 +129,258 @@ int forward (
return 0;
}
#ifdef ZMQ_HAVE_POLLER
int zmq::proxy (
class socket_base_t *frontend_,
class socket_base_t *backend_,
class socket_base_t *capture_,
class socket_base_t *control_)
{
msg_t msg;
int rc = msg.init ();
if (rc != 0)
return -1;
// The algorithm below assumes ratio of requests and replies processed
// under full load to be 1:1.
int more;
size_t moresz = sizeof (more);
// Proxy can be in these three states
enum {
active,
paused,
terminated
} state = active;
bool frontend_equal_to_backend;
bool frontend_in = false;
bool frontend_out = false;
bool backend_in = false;
bool backend_out = false;
bool control_in = false;
zmq::socket_poller_t::event_t events [3];
// Don't allocate these pollers from stack because they will take more than 900 kB of stack!
// On Windows this blows up default stack of 1 MB and aborts the program.
// I wanted to use std::shared_ptr here as the best solution but that requires C++11...
zmq::socket_poller_t *poller_all = new (std::nothrow) zmq::socket_poller_t; // Poll for everything.
zmq::socket_poller_t *poller_in = new (std::nothrow) zmq::socket_poller_t; // Poll only 'ZMQ_POLLIN' on all sockets. Initial blocking poll in loop.
zmq::socket_poller_t *poller_control = new (std::nothrow) zmq::socket_poller_t; // Poll only for 'ZMQ_POLLIN' on 'control_', when proxy is paused.
zmq::socket_poller_t *poller_receive_blocked = new (std::nothrow) zmq::socket_poller_t; // All except 'ZMQ_POLLIN' on 'frontend_'.
// If frontend_==backend_ 'poller_send_blocked' and 'poller_receive_blocked' are the same, 'ZMQ_POLLIN' is ignored.
// In that case 'poller_send_blocked' is not used. We need only 'poller_receive_blocked'.
// We also don't need 'poller_both_blocked', no need to initialize it.
// We save some RAM and time for initialization.
zmq::socket_poller_t *poller_send_blocked = NULL; // All except 'ZMQ_POLLIN' on 'backend_'.
zmq::socket_poller_t *poller_both_blocked = NULL; // All except 'ZMQ_POLLIN' on both 'frontend_' and 'backend_'.
if (frontend_ != backend_) {
poller_send_blocked = new (std::nothrow) zmq::socket_poller_t; // All except 'ZMQ_POLLIN' on 'backend_'.
poller_both_blocked = new (std::nothrow) zmq::socket_poller_t; // All except 'ZMQ_POLLIN' on both 'frontend_' and 'backend_'.
frontend_equal_to_backend = false;
} else
frontend_equal_to_backend = true;
if (poller_all == NULL || poller_in == NULL || poller_control == NULL || poller_receive_blocked == NULL
|| ((poller_send_blocked == NULL || poller_both_blocked == NULL) && !frontend_equal_to_backend)) {
PROXY_CLEANUP ();
return close_and_return (&msg, -1);
}
zmq::socket_poller_t *poller_wait = poller_in; // Poller for blocking wait, initially all 'ZMQ_POLLIN'.
// Register 'frontend_' and 'backend_' with pollers.
rc = poller_all->add (frontend_, NULL, ZMQ_POLLIN | ZMQ_POLLOUT); // Everything.
CHECK_RC_EXIT_ON_FAILURE ();
rc = poller_in->add (frontend_, NULL, ZMQ_POLLIN); // All 'ZMQ_POLLIN's.
CHECK_RC_EXIT_ON_FAILURE ();
if (frontend_equal_to_backend) {
// If frontend_==backend_ 'poller_send_blocked' and 'poller_receive_blocked' are the same,
// so we don't need 'poller_send_blocked'. We need only 'poller_receive_blocked'.
// We also don't need 'poller_both_blocked', no need to initialize it.
rc = poller_receive_blocked->add (frontend_, NULL, ZMQ_POLLOUT);
CHECK_RC_EXIT_ON_FAILURE ();
} else {
rc = poller_all->add (backend_, NULL, ZMQ_POLLIN | ZMQ_POLLOUT); // Everything.
CHECK_RC_EXIT_ON_FAILURE ();
rc = poller_in->add (backend_, NULL, ZMQ_POLLIN); // All 'ZMQ_POLLIN's.
CHECK_RC_EXIT_ON_FAILURE ();
rc = poller_both_blocked->add (frontend_, NULL, ZMQ_POLLOUT); // Waiting only for 'ZMQ_POLLOUT'.
CHECK_RC_EXIT_ON_FAILURE ();
rc = poller_both_blocked->add (backend_, NULL, ZMQ_POLLOUT); // Waiting only for 'ZMQ_POLLOUT'.
CHECK_RC_EXIT_ON_FAILURE ();
rc = poller_send_blocked->add (backend_, NULL, ZMQ_POLLOUT); // All except 'ZMQ_POLLIN' on 'backend_'.
CHECK_RC_EXIT_ON_FAILURE ();
rc = poller_send_blocked->add (frontend_, NULL, ZMQ_POLLIN | ZMQ_POLLOUT); // All except 'ZMQ_POLLIN' on 'backend_'.
CHECK_RC_EXIT_ON_FAILURE ();
rc = poller_receive_blocked->add (frontend_, NULL, ZMQ_POLLOUT); // All except 'ZMQ_POLLIN' on 'frontend_'.
CHECK_RC_EXIT_ON_FAILURE ();
rc = poller_receive_blocked->add (backend_, NULL, ZMQ_POLLIN | ZMQ_POLLOUT); // All except 'ZMQ_POLLIN' on 'frontend_'.
CHECK_RC_EXIT_ON_FAILURE ();
}
// Register 'control_' with pollers.
if (control_ != NULL) {
rc = poller_all->add (control_, NULL, ZMQ_POLLIN);
CHECK_RC_EXIT_ON_FAILURE ();
rc = poller_in->add (control_, NULL, ZMQ_POLLIN);
CHECK_RC_EXIT_ON_FAILURE ();
rc = poller_control->add (control_, NULL, ZMQ_POLLIN); // When proxy is paused we wait only for ZMQ_POLLIN on 'control_' socket.
CHECK_RC_EXIT_ON_FAILURE ();
rc = poller_receive_blocked->add (control_, NULL, ZMQ_POLLIN);
CHECK_RC_EXIT_ON_FAILURE ();
if (!frontend_equal_to_backend) {
rc = poller_send_blocked->add (control_, NULL, ZMQ_POLLIN);
CHECK_RC_EXIT_ON_FAILURE ();
rc = poller_both_blocked->add (control_, NULL, ZMQ_POLLIN);
CHECK_RC_EXIT_ON_FAILURE ();
}
}
int i;
bool request_processed, reply_processed;
while (state != terminated) {
// Blocking wait initially only for 'ZMQ_POLLIN' - 'poller_wait' points to 'poller_in'.
// If one of receiving end's queue is full ('ZMQ_POLLOUT' not available),
// 'poller_wait' is pointed to 'poller_receive_blocked', 'poller_send_blocked' or 'poller_both_blocked'.
rc = poller_wait->wait (events, 3, -1);
if (rc < 0 && errno == ETIMEDOUT)
rc = 0;
CHECK_RC_EXIT_ON_FAILURE ();
// Some of events waited for by 'poller_wait' have arrived, now poll for everything without blocking.
rc = poller_all->wait (events, 3, 0);
if (rc < 0 && errno == ETIMEDOUT)
rc = 0;
CHECK_RC_EXIT_ON_FAILURE ();
// Process events.
for (i = 0; i < rc; i++) {
if (events [i].socket == frontend_) {
frontend_in = (events [i].events & ZMQ_POLLIN) != 0;
frontend_out = (events [i].events & ZMQ_POLLOUT) != 0;
} else
// This 'if' needs to be after check for 'frontend_' in order never
// to be reached in case frontend_==backend_, so we ensure backend_in=false in that case.
if (events [i].socket == backend_) {
backend_in = (events [i].events & ZMQ_POLLIN) != 0;
backend_out = (events [i].events & ZMQ_POLLOUT) != 0;
} else
if (events [i].socket == control_)
control_in = (events [i].events & ZMQ_POLLIN) != 0;
}
// Process a control command if any.
if (control_in) {
rc = control_->recv (&msg, 0);
CHECK_RC_EXIT_ON_FAILURE ();
rc = control_->getsockopt (ZMQ_RCVMORE, &more, &moresz);
if (unlikely (rc < 0) || more) {
PROXY_CLEANUP ();
return close_and_return (&msg, -1);
}
// Copy message to capture socket if any.
rc = capture (capture_, msg);
CHECK_RC_EXIT_ON_FAILURE ();
if (msg.size () == 5 && memcmp (msg.data (), "PAUSE", 5) == 0) {
state = paused;
poller_wait = poller_control;
} else
if (msg.size () == 6 && memcmp (msg.data (), "RESUME", 6) == 0) {
state = active;
poller_wait = poller_in;
} else
if (msg.size () == 9 && memcmp (msg.data (), "TERMINATE", 9) == 0)
state = terminated;
else {
// This is an API error, we assert
puts ("E: invalid command sent to proxy");
zmq_assert (false);
}
control_in = false;
}
if (state == active) {
// Process a request, 'ZMQ_POLLIN' on 'frontend_' and 'ZMQ_POLLOUT' on 'backend_'.
// In case of frontend_==backend_ there's no 'ZMQ_POLLOUT' event.
if (frontend_in && (backend_out || frontend_equal_to_backend)) {
rc = forward (frontend_, backend_, capture_, msg);
CHECK_RC_EXIT_ON_FAILURE ();
request_processed = true;
frontend_in = backend_out = false;
} else request_processed = false;
// Process a reply, 'ZMQ_POLLIN' on 'backend_' and 'ZMQ_POLLOUT' on 'frontend_'.
// If 'frontend_' and 'backend_' are the same this is not needed because previous processing
// covers all of the cases. 'backend_in' is always false if frontend_==backend_ due to
// design in 'for' event processing loop.
if (backend_in && frontend_out) {
rc = forward (backend_, frontend_, capture_, msg);
CHECK_RC_EXIT_ON_FAILURE ();
reply_processed = true;
backend_in = frontend_out = false;
} else reply_processed = false;
if (request_processed || reply_processed) {
// If request/reply is processed that means we had at least one 'ZMQ_POLLOUT' event.
// Enable corresponding 'ZMQ_POLLIN' for blocking wait if any was disabled.
if (poller_wait != poller_in) {
if (request_processed) { // 'frontend_' -> 'backend_'
if (poller_wait == poller_both_blocked)
poller_wait = poller_send_blocked;
else
if (poller_wait == poller_receive_blocked)
poller_wait = poller_in;
}
if (reply_processed) { // 'backend_' -> 'frontend_'
if (poller_wait == poller_both_blocked)
poller_wait = poller_receive_blocked;
else
if (poller_wait == poller_send_blocked)
poller_wait = poller_in;
}
}
} else {
// No requests have been processed, there were no 'ZMQ_POLLOUT' events.
// That means that receiving end queue(s) is/are full.
// Disable receiving 'ZMQ_POLLIN' for sockets for which there's no 'ZMQ_POLLOUT'.
if (frontend_in) {
if (poller_wait == poller_send_blocked)
poller_wait = poller_both_blocked;
else
poller_wait = poller_receive_blocked;
}
if (backend_in) {
// Will never be reached if frontend_==backend_, 'backend_in' will
// always be false due to design in 'for' event processing loop.
if (poller_wait == poller_receive_blocked)
poller_wait = poller_both_blocked;
else
poller_wait = poller_send_blocked;
}
}
}
}
PROXY_CLEANUP ();
return close_and_return (&msg, 0);
}
#else // ZMQ_HAVE_POLLER
int zmq::proxy (
class socket_base_t *frontend_,
class socket_base_t *backend_,
@@ -206,3 +482,5 @@ int zmq::proxy (
return close_and_return (&msg, 0);
}
#endif // ZMQ_HAVE_POLLER