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direwolf/tq.c

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//
// This file is part of Dire Wolf, an amateur radio packet TNC.
//
// Copyright (C) 2011, 2012, 2014, 2015 John Langner, WB2OSZ
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 2 of the License, or
// (at your option) any later version.
//
// This program 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
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
/*------------------------------------------------------------------
*
* Module: tq.c
*
* Purpose: Transmit queue - hold packets for transmission until the channel is clear.
*
* Description: Producers of packets to be transmitted call tq_append and then
* go merrily on their way, unconcerned about when the packet might
* actually get transmitted.
*
* Another thread waits until the channel is clear and then removes
* packets from the queue and transmits them.
*
* Revisions: 1.2 - Enhance for multiple audio devices.
*
*---------------------------------------------------------------*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include "direwolf.h"
#include "ax25_pad.h"
#include "textcolor.h"
#include "audio.h"
#include "tq.h"
#include "dedupe.h"
static packet_t queue_head[MAX_CHANS][TQ_NUM_PRIO]; /* Head of linked list for each queue. */
static dw_mutex_t tq_mutex; /* Critical section for updating queues. */
/* Just one for all queues. */
#if __WIN32__
static HANDLE wake_up_event[MAX_CHANS]; /* Notify transmit thread when queue not empty. */
#else
static pthread_cond_t wake_up_cond[MAX_CHANS]; /* Notify transmit thread when queue not empty. */
static pthread_mutex_t wake_up_mutex[MAX_CHANS]; /* Required by cond_wait. */
static int xmit_thread_is_waiting[MAX_CHANS];
#endif
static int tq_is_empty (int chan);
/*-------------------------------------------------------------------
*
* Name: tq_init
*
* Purpose: Initialize the transmit queue.
*
* Inputs: audio_config_p - Audio device configuration.
*
* Outputs:
*
* Description: Initialize the queue to be empty and set up other
* mechanisms for sharing it between different threads.
*
* We have different timing rules for different types of
* packets so they are put into different queues.
*
* High Priority -
*
* Packets which are being digipeated go out first.
* Latest recommendations are to retransmit these
* immdediately (after no one else is heard, of course)
* rather than waiting random times to avoid collisions.
* The KPC-3 configuration option for this is "UIDWAIT OFF".
*
* Low Priority -
*
* Other packets are sent after a random wait time
* (determined by PERSIST & SLOTTIME) to help avoid
* collisions.
*
* Each audio channel has its own queue.
*
*--------------------------------------------------------------------*/
static struct audio_s *save_audio_config_p;
void tq_init (struct audio_s *audio_config_p)
{
int c, p;
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_init ( %d )\n", nchan);
#endif
save_audio_config_p = audio_config_p;
for (c=0; c<MAX_CHANS; c++) {
for (p=0; p<TQ_NUM_PRIO; p++) {
queue_head[c][p] = NULL;
}
}
/*
* Mutex to coordinate access to the queue.
*/
dw_mutex_init(&tq_mutex);
/*
* Windows and Linux have different wake up methods.
* Put a wrapper around this someday to hide the details.
*/
#if __WIN32__
for (c = 0; c < MAX_CHANS; c++) {
if (audio_config_p->achan[c].valid) {
wake_up_event[c] = CreateEvent (NULL, 0, 0, NULL);
if (wake_up_event[c] == NULL) {
text_color_set(DW_COLOR_ERROR);
dw_printf ("tq_init: CreateEvent: can't create transmit wake up event, c=%d", c);
exit (1);
}
}
}
#else
int err;
for (c = 0; c < MAX_CHANS; c++) {
xmit_thread_is_waiting[c] = 0;
if (audio_config_p->achan[c].valid) {
err = pthread_cond_init (&(wake_up_cond[c]), NULL);
if (err != 0) {
text_color_set(DW_COLOR_ERROR);
dw_printf ("tq_init: pthread_cond_init c=%d err=%d", c, err);
perror ("");
exit (1);
}
dw_mutex_init(&(wake_up_mutex[c]));
}
}
#endif
} /* end tq_init */
/*-------------------------------------------------------------------
*
* Name: tq_append
*
* Purpose: Add a packet to the end of the specified transmit queue.
*
* Inputs: chan - Channel, 0 is first.
*
* prio - Priority, use TQ_PRIO_0_HI or TQ_PRIO_1_LO.
*
* pp - Address of packet object.
* Caller should NOT make any references to
* it after this point because it could
* be deleted at any time.
*
* Outputs:
*
* Description: Add packet to end of linked list.
* Signal the transmit thread if the queue was formerly empty.
*
* Note that we have a transmit thread each audio channel.
* Two channels can share one audio output device.
*
* IMPORTANT! Don't make an further references to the packet object after
* giving it to tq_append.
*
*--------------------------------------------------------------------*/
void tq_append (int chan, int prio, packet_t pp)
{
packet_t plast;
packet_t pnext;
//int a = ACHAN2ADEV(chan); /* Audio device for channel. */
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_append (chan=%d, prio=%d, pp=%p)\n", chan, prio, pp);
#endif
assert (chan >= 0 && chan < MAX_CHANS);
assert (prio >= 0 && prio < TQ_NUM_PRIO);
#if AX25MEMDEBUG
if (ax25memdebug_get()) {
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_append (chan=%d, prio=%d, seq=%d)\n", chan, prio, ax25memdebug_seq(pp));
}
#endif
if ( ! save_audio_config_p->achan[chan].valid) {
text_color_set(DW_COLOR_ERROR);
dw_printf ("ERROR - Request to transmit on invalid radio channel %d.\n", chan);
ax25_delete(pp);
return;
}
/*
* Is transmit queue out of control?
*
* There is no technical reason to limit the transmit packet queue length, it just seemed like a good
* warning that something wasn<73>t right.
* When this was written, I was mostly concerned about APRS where packets would only be sent
* occasionally and they can be discarded if they can<61>t be sent out in a reasonable amount of time.
*
* If a large file is being sent, with TCP/IP, it is perfectly reasonable to have a large number
* of packets waiting for transmission.
*
* Ideally, the application should be able to throttle the transmissions so the queue doesn't get too long.
* If using the KISS interface, there is no way to get this information from the TNC back to the client app.
* The AGW network interface does have a command <20>y<EFBFBD> to query about the number of frames waiting for transmission.
* This was implemented in version 1.2.
*
* I'd rather not take out the queue length check because it is a useful sanity check for something going wrong.
* Maybe the check should be performed only for APRS packets.
* The check would allow an unlimited number of other types.
*
* Limit was 20. Changed to 100 in version 1.2 as a workaround.
*
* Implementing the 6PACK protocol is probably the proper solution.
*/
if (ax25_is_aprs(pp) && tq_count(chan,prio) > 100) {
text_color_set(DW_COLOR_ERROR);
dw_printf ("Transmit packet queue for channel %d is too long. Discarding packet.\n", chan);
dw_printf ("Perhaps the channel is so busy there is no opportunity to send.\n");
ax25_delete(pp);
return;
}
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_append: enter critical section\n");
#endif
dw_mutex_lock (&tq_mutex);
// was_empty = 1;
// for (c=0; c<tq_num_channels; c++) {
// for (p=0; p<TQ_NUM_PRIO; p++) {
// if (queue_head[c][p] != NULL)
// was_empty = 0;
// }
// }
if (queue_head[chan][prio] == NULL) {
queue_head[chan][prio] = pp;
}
else {
plast = queue_head[chan][prio];
while ((pnext = ax25_get_nextp(plast)) != NULL) {
plast = pnext;
}
ax25_set_nextp (plast, pp);
}
dw_mutex_unlock (&tq_mutex);
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_append: left critical section\n");
dw_printf ("tq_append (): about to wake up xmit thread.\n");
#endif
#if __WIN32__
SetEvent (wake_up_event[chan]);
#else
if (xmit_thread_is_waiting[chan]) {
int err;
dw_mutex_lock (&(wake_up_mutex[chan]));
err = pthread_cond_signal (&(wake_up_cond[chan]));
if (err != 0) {
text_color_set(DW_COLOR_ERROR);
dw_printf ("tq_append: pthread_cond_signal err=%d", err);
perror ("");
exit (1);
}
dw_mutex_unlock (&(wake_up_mutex[chan]));
}
#endif
}
/*-------------------------------------------------------------------
*
* Name: tq_wait_while_empty
*
* Purpose: Sleep while the transmit queue is empty rather than
* polling periodically.
*
* Inputs: chan - Audio device number.
*
* Description: We have one transmit thread for each audio device.
* This handles 1 or 2 channels.
*
*--------------------------------------------------------------------*/
void tq_wait_while_empty (int chan)
{
int is_empty;
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_wait_while_empty (%d) : enter critical section\n", chan);
#endif
assert (chan >= 0 && chan < MAX_CHANS);
dw_mutex_lock (&tq_mutex);
#if DEBUG
//text_color_set(DW_COLOR_DEBUG);
//dw_printf ("tq_wait_while_empty (%d): after pthread_mutex_lock\n", chan);
#endif
is_empty = tq_is_empty(chan);
dw_mutex_unlock (&tq_mutex);
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_wait_while_empty (%d) : left critical section\n", chan);
#endif
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_wait_while_empty (%d): is_empty = %d\n", chan, is_empty);
#endif
if (is_empty) {
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_wait_while_empty (%d): SLEEP - about to call cond wait\n", chan);
#endif
#if __WIN32__
WaitForSingleObject (wake_up_event[chan], INFINITE);
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_wait_while_empty (): returned from wait\n");
#endif
#else
dw_mutex_lock (&(wake_up_mutex[chan]));
xmit_thread_is_waiting[chan] = 1;
int err;
err = pthread_cond_wait (&(wake_up_cond[chan]), &(wake_up_mutex[chan]));
xmit_thread_is_waiting[chan] = 0;
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_wait_while_empty (%d): WOKE UP - returned from cond wait, err = %d\n", chan, err);
#endif
if (err != 0) {
text_color_set(DW_COLOR_ERROR);
dw_printf ("tq_wait_while_empty (%d): pthread_cond_wait err=%d", chan, err);
perror ("");
exit (1);
}
dw_mutex_unlock (&(wake_up_mutex[chan]));
#endif
}
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_wait_while_empty (%d) returns\n", chan);
#endif
}
/*-------------------------------------------------------------------
*
* Name: tq_remove
*
* Purpose: Remove a packet from the head of the specified transmit queue.
*
* Inputs: chan - Channel, 0 is first.
*
* prio - Priority, use TQ_PRIO_0_HI or TQ_PRIO_1_LO.
*
* Returns: Pointer to packet object.
* Caller should destroy it with ax25_delete when finished with it.
*
*--------------------------------------------------------------------*/
packet_t tq_remove (int chan, int prio)
{
packet_t result_p;
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_remove(%d,%d) enter critical section\n", chan, prio);
#endif
dw_mutex_lock (&tq_mutex);
if (queue_head[chan][prio] == NULL) {
result_p = NULL;
}
else {
result_p = queue_head[chan][prio];
queue_head[chan][prio] = ax25_get_nextp(result_p);
ax25_set_nextp (result_p, NULL);
}
dw_mutex_unlock (&tq_mutex);
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_remove(%d,%d) leave critical section, returns %p\n", chan, prio, result_p);
#endif
#if AX25MEMDEBUG
if (ax25memdebug_get() && result_p != NULL) {
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_remove (chan=%d, prio=%d) seq=%d\n", chan, prio, ax25memdebug_seq(result_p));
}
#endif
return (result_p);
}
/*-------------------------------------------------------------------
*
* Name: tq_is_empty
*
* Purpose: Test if queues for specified channel are empty.
*
* Inputs: chan Channel
*
* Returns: True if nothing in the queue.
*
*--------------------------------------------------------------------*/
static int tq_is_empty (int chan)
{
int p;
assert (chan >= 0 && chan < MAX_CHANS);
for (p=0; p<TQ_NUM_PRIO; p++) {
assert (p >= 0 && p < TQ_NUM_PRIO);
if (queue_head[chan][p] != NULL)
return (0);
}
return (1);
} /* end tq_is_empty */
/*-------------------------------------------------------------------
*
* Name: tq_count
*
* Purpose: Return count of the number of packets in the specified transmit queue.
*
* Inputs: chan - Channel, 0 is first.
*
* prio - Priority, use TQ_PRIO_0_HI or TQ_PRIO_1_LO.
*
* Returns: Number of items in specified queue.
*
*--------------------------------------------------------------------*/
int tq_count (int chan, int prio)
{
packet_t p;
int n;
/* Don't bother with critical section. */
/* Only used for debugging a problem. */
n = 0;
p = queue_head[chan][prio];
while (p != NULL) {
n++;
p = ax25_get_nextp(p);
}
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("tq_count(%d,%d) returns %d\n", chan, prio, n);
#endif
return (n);
} /* end tq_count */
/* end tq.c */
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