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klipper/klippy/chelper/serialqueue.c

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// Serial port command queuing
//
// Copyright (C) 2016-2021 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
// This goal of this code is to handle low-level serial port
// communications with a microcontroller (mcu). This code is written
// in C (instead of python) to reduce communication latencies and to
// reduce scheduling jitter. The code queues messages to be
// transmitted, schedules transmission of commands at specified mcu
// clock times, prioritizes commands, and handles retransmissions. A
// background thread is launched to do this work and minimize latency.
#include <linux/can.h> // // struct can_frame
#include <math.h> // fabs
#include <pthread.h> // pthread_mutex_lock
#include <stddef.h> // offsetof
#include <stdint.h> // uint64_t
#include <stdio.h> // snprintf
#include <stdlib.h> // malloc
#include <string.h> // memset
#include <termios.h> // tcflush
#include <unistd.h> // pipe
#include "compiler.h" // __visible
#include "list.h" // list_add_tail
#include "msgblock.h" // message_alloc
#include "pollreactor.h" // pollreactor_alloc
#include "pyhelper.h" // get_monotonic
#include "serialqueue.h" // struct queue_message
struct command_queue {
struct list_head stalled_queue, ready_queue;
struct list_node node;
};
struct serialqueue {
// Input reading
struct pollreactor *pr;
int serial_fd, serial_fd_type, client_id;
int pipe_fds[2];
uint8_t input_buf[4096];
uint8_t need_sync;
int input_pos;
// Threading
pthread_t tid;
pthread_mutex_t lock; // protects variables below
pthread_cond_t cond;
int receive_waiting;
// Baud / clock tracking
int receive_window;
double baud_adjust, idle_time;
struct clock_estimate ce;
double last_receive_sent_time;
// Retransmit support
uint64_t send_seq, receive_seq;
uint64_t ignore_nak_seq, last_ack_seq, retransmit_seq, rtt_sample_seq;
struct list_head sent_queue;
double srtt, rttvar, rto;
// Pending transmission message queues
struct list_head pending_queues;
int ready_bytes, stalled_bytes, need_ack_bytes, last_ack_bytes;
uint64_t need_kick_clock;
struct list_head notify_queue;
// Received messages
struct list_head receive_queue;
// Fastreader support
pthread_mutex_t fast_reader_dispatch_lock;
struct list_head fast_readers;
// Debugging
struct list_head old_sent, old_receive;
// Stats
uint32_t bytes_write, bytes_read, bytes_retransmit, bytes_invalid;
};
#define SQPF_SERIAL 0
#define SQPF_PIPE 1
#define SQPF_NUM 2
#define SQPT_RETRANSMIT 0
#define SQPT_COMMAND 1
#define SQPT_NUM 2
#define SQT_UART 'u'
#define SQT_CAN 'c'
#define SQT_DEBUGFILE 'f'
#define MIN_RTO 0.025
#define MAX_RTO 5.000
#define MAX_PENDING_BLOCKS 12
#define MIN_REQTIME_DELTA 0.250
#define MIN_BACKGROUND_DELTA 0.005
#define IDLE_QUERY_TIME 1.0
#define DEBUG_QUEUE_SENT 100
#define DEBUG_QUEUE_RECEIVE 100
// Create a series of empty messages and add them to a list
static void
debug_queue_alloc(struct list_head *root, int count)
{
int i;
for (i=0; i<count; i++) {
struct queue_message *qm = message_alloc();
list_add_head(&qm->node, root);
}
}
// Copy a message to a debug queue and free old debug messages
static void
debug_queue_add(struct list_head *root, struct queue_message *qm)
{
list_add_tail(&qm->node, root);
struct queue_message *old = list_first_entry(
root, struct queue_message, node);
list_del(&old->node);
message_free(old);
}
// Wake up the receiver thread if it is waiting
static void
check_wake_receive(struct serialqueue *sq)
{
if (sq->receive_waiting) {
sq->receive_waiting = 0;
pthread_cond_signal(&sq->cond);
}
}
// Write to the internal pipe to wake the background thread if in poll
static void
kick_bg_thread(struct serialqueue *sq)
{
int ret = write(sq->pipe_fds[1], ".", 1);
if (ret < 0)
report_errno("pipe write", ret);
}
// Update internal state when the receive sequence increases
static void
update_receive_seq(struct serialqueue *sq, double eventtime, uint64_t rseq)
{
// Remove from sent queue
uint64_t sent_seq = sq->receive_seq;
for (;;) {
struct queue_message *sent = list_first_entry(
&sq->sent_queue, struct queue_message, node);
if (list_empty(&sq->sent_queue)) {
// Got an ack for a message not sent; must be connection init
sq->send_seq = rseq;
sq->last_receive_sent_time = 0.;
break;
}
sq->need_ack_bytes -= sent->len;
list_del(&sent->node);
debug_queue_add(&sq->old_sent, sent);
sent_seq++;
if (rseq == sent_seq) {
// Found sent message corresponding with the received sequence
sq->last_receive_sent_time = sent->receive_time;
sq->last_ack_bytes = sent->len;
break;
}
}
sq->receive_seq = rseq;
pollreactor_update_timer(sq->pr, SQPT_COMMAND, PR_NOW);
// Update retransmit info
if (sq->rtt_sample_seq && rseq > sq->rtt_sample_seq
&& sq->last_receive_sent_time) {
// RFC6298 rtt calculations
double delta = eventtime - sq->last_receive_sent_time;
if (!sq->srtt) {
sq->rttvar = delta / 2.0;
sq->srtt = delta * 10.0; // use a higher start default
} else {
sq->rttvar = (3.0 * sq->rttvar + fabs(sq->srtt - delta)) / 4.0;
sq->srtt = (7.0 * sq->srtt + delta) / 8.0;
}
double rttvar4 = sq->rttvar * 4.0;
if (rttvar4 < 0.001)
rttvar4 = 0.001;
sq->rto = sq->srtt + rttvar4;
if (sq->rto < MIN_RTO)
sq->rto = MIN_RTO;
else if (sq->rto > MAX_RTO)
sq->rto = MAX_RTO;
sq->rtt_sample_seq = 0;
}
if (list_empty(&sq->sent_queue)) {
pollreactor_update_timer(sq->pr, SQPT_RETRANSMIT, PR_NEVER);
} else {
struct queue_message *sent = list_first_entry(
&sq->sent_queue, struct queue_message, node);
double nr = eventtime + sq->rto + sent->len * sq->baud_adjust;
pollreactor_update_timer(sq->pr, SQPT_RETRANSMIT, nr);
}
}
// Process a well formed input message
static void
handle_message(struct serialqueue *sq, double eventtime, int len)
{
pthread_mutex_lock(&sq->lock);
// Calculate receive sequence number
uint64_t rseq = ((sq->receive_seq & ~MESSAGE_SEQ_MASK)
| (sq->input_buf[MESSAGE_POS_SEQ] & MESSAGE_SEQ_MASK));
if (rseq != sq->receive_seq) {
// New sequence number
if (rseq < sq->receive_seq)
rseq += MESSAGE_SEQ_MASK+1;
if (rseq > sq->send_seq && sq->receive_seq != 1) {
// An ack for a message not sent? Out of order message?
sq->bytes_invalid += len;
pthread_mutex_unlock(&sq->lock);
return;
}
update_receive_seq(sq, eventtime, rseq);
}
sq->bytes_read += len;
// Check for pending messages on notify_queue
int must_wake = 0;
while (!list_empty(&sq->notify_queue)) {
struct queue_message *qm = list_first_entry(
&sq->notify_queue, struct queue_message, node);
uint64_t wake_seq = rseq - 1 - (len > MESSAGE_MIN ? 1 : 0);
uint64_t notify_msg_sent_seq = qm->req_clock;
if (notify_msg_sent_seq > wake_seq)
break;
list_del(&qm->node);
qm->len = 0;
qm->sent_time = sq->last_receive_sent_time;
qm->receive_time = eventtime;
list_add_tail(&qm->node, &sq->receive_queue);
must_wake = 1;
}
// Process message
if (len == MESSAGE_MIN) {
// Ack/nak message
if (sq->last_ack_seq < rseq)
sq->last_ack_seq = rseq;
else if (rseq > sq->ignore_nak_seq && !list_empty(&sq->sent_queue))
// Duplicate Ack is a Nak - do fast retransmit
pollreactor_update_timer(sq->pr, SQPT_RETRANSMIT, PR_NOW);
} else {
// Data message - add to receive queue
struct queue_message *qm = message_fill(sq->input_buf, len);
qm->sent_time = (rseq > sq->retransmit_seq
? sq->last_receive_sent_time : 0.);
qm->receive_time = get_monotonic(); // must be time post read()
qm->receive_time -= sq->baud_adjust * len;
list_add_tail(&qm->node, &sq->receive_queue);
must_wake = 1;
}
// Check fast readers
struct fastreader *fr;
list_for_each_entry(fr, &sq->fast_readers, node) {
if (len < fr->prefix_len + MESSAGE_MIN
|| memcmp(&sq->input_buf[MESSAGE_HEADER_SIZE]
, fr->prefix, fr->prefix_len) != 0)
continue;
// Release main lock and invoke callback
pthread_mutex_lock(&sq->fast_reader_dispatch_lock);
if (must_wake)
check_wake_receive(sq);
pthread_mutex_unlock(&sq->lock);
fr->func(fr, sq->input_buf, len);
pthread_mutex_unlock(&sq->fast_reader_dispatch_lock);
return;
}
if (must_wake)
check_wake_receive(sq);
pthread_mutex_unlock(&sq->lock);
}
// Callback for input activity on the serial fd
static void
input_event(struct serialqueue *sq, double eventtime)
{
if (sq->serial_fd_type == SQT_CAN) {
struct can_frame cf;
int ret = read(sq->serial_fd, &cf, sizeof(cf));
if (ret <= 0) {
report_errno("can read", ret);
pollreactor_do_exit(sq->pr);
return;
}
if (cf.can_id != sq->client_id + 1)
return;
memcpy(&sq->input_buf[sq->input_pos], cf.data, cf.can_dlc);
sq->input_pos += cf.can_dlc;
} else {
int ret = read(sq->serial_fd, &sq->input_buf[sq->input_pos]
, sizeof(sq->input_buf) - sq->input_pos);
if (ret <= 0) {
if(ret < 0)
report_errno("read", ret);
else
errorf("Got EOF when reading from device");
pollreactor_do_exit(sq->pr);
return;
}
sq->input_pos += ret;
}
for (;;) {
int len = msgblock_check(&sq->need_sync, sq->input_buf, sq->input_pos);
if (!len)
// Need more data
return;
if (len > 0) {
// Received a valid message
handle_message(sq, eventtime, len);
} else {
// Skip bad data at beginning of input
len = -len;
pthread_mutex_lock(&sq->lock);
sq->bytes_invalid += len;
pthread_mutex_unlock(&sq->lock);
}
sq->input_pos -= len;
if (sq->input_pos)
memmove(sq->input_buf, &sq->input_buf[len], sq->input_pos);
}
}
// Callback for input activity on the pipe fd (wakes command_event)
static void
kick_event(struct serialqueue *sq, double eventtime)
{
char dummy[4096];
int ret = read(sq->pipe_fds[0], dummy, sizeof(dummy));
if (ret < 0)
report_errno("pipe read", ret);
pollreactor_update_timer(sq->pr, SQPT_COMMAND, PR_NOW);
}
static void
do_write(struct serialqueue *sq, void *buf, int buflen)
{
if (sq->serial_fd_type != SQT_CAN) {
int ret = write(sq->serial_fd, buf, buflen);
if (ret < 0)
report_errno("write", ret);
return;
}
// Write to CAN fd
struct can_frame cf;
while (buflen) {
int size = buflen > 8 ? 8 : buflen;
cf.can_id = sq->client_id;
cf.can_dlc = size;
memcpy(cf.data, buf, size);
int ret = write(sq->serial_fd, &cf, sizeof(cf));
if (ret < 0) {
report_errno("can write", ret);
return;
}
buf += size;
buflen -= size;
}
}
// Callback timer for when a retransmit should be done
static double
retransmit_event(struct serialqueue *sq, double eventtime)
{
if (sq->serial_fd_type == SQT_UART) {
int ret = tcflush(sq->serial_fd, TCOFLUSH);
if (ret < 0)
report_errno("tcflush", ret);
}
pthread_mutex_lock(&sq->lock);
// Retransmit all pending messages
uint8_t buf[MESSAGE_MAX * MAX_PENDING_BLOCKS + 1];
int buflen = 0, first_buflen = 0;
buf[buflen++] = MESSAGE_SYNC;
struct queue_message *qm;
list_for_each_entry(qm, &sq->sent_queue, node) {
memcpy(&buf[buflen], qm->msg, qm->len);
buflen += qm->len;
if (!first_buflen)
first_buflen = qm->len + 1;
}
do_write(sq, buf, buflen);
sq->bytes_retransmit += buflen;
// Update rto
if (pollreactor_get_timer(sq->pr, SQPT_RETRANSMIT) == PR_NOW) {
// Retransmit due to nak
sq->ignore_nak_seq = sq->receive_seq;
if (sq->receive_seq < sq->retransmit_seq)
// Second nak for this retransmit - don't allow third
sq->ignore_nak_seq = sq->retransmit_seq;
} else {
// Retransmit due to timeout
sq->rto *= 2.0;
if (sq->rto > MAX_RTO)
sq->rto = MAX_RTO;
sq->ignore_nak_seq = sq->send_seq;
}
sq->retransmit_seq = sq->send_seq;
sq->rtt_sample_seq = 0;
sq->idle_time = eventtime + buflen * sq->baud_adjust;
double waketime = eventtime + first_buflen * sq->baud_adjust + sq->rto;
pthread_mutex_unlock(&sq->lock);
return waketime;
}
// Construct a block of data to be sent to the serial port
static int
build_and_send_command(struct serialqueue *sq, uint8_t *buf, double eventtime)
{
int len = MESSAGE_HEADER_SIZE;
while (sq->ready_bytes) {
// Find highest priority message (message with lowest req_clock)
uint64_t min_clock = MAX_CLOCK;
struct command_queue *q, *cq = NULL;
struct queue_message *qm = NULL;
list_for_each_entry(q, &sq->pending_queues, node) {
if (!list_empty(&q->ready_queue)) {
struct queue_message *m = list_first_entry(
&q->ready_queue, struct queue_message, node);
if (m->req_clock < min_clock) {
min_clock = m->req_clock;
cq = q;
qm = m;
}
}
}
// Append message to outgoing command
if (len + qm->len > MESSAGE_MAX - MESSAGE_TRAILER_SIZE)
break;
list_del(&qm->node);
if (list_empty(&cq->ready_queue) && list_empty(&cq->stalled_queue))
list_del(&cq->node);
memcpy(&buf[len], qm->msg, qm->len);
len += qm->len;
sq->ready_bytes -= qm->len;
if (qm->notify_id) {
// Message requires notification - add to notify list
qm->req_clock = sq->send_seq;
list_add_tail(&qm->node, &sq->notify_queue);
} else {
message_free(qm);
}
}
// Fill header / trailer
len += MESSAGE_TRAILER_SIZE;
buf[MESSAGE_POS_LEN] = len;
buf[MESSAGE_POS_SEQ] = MESSAGE_DEST | (sq->send_seq & MESSAGE_SEQ_MASK);
uint16_t crc = msgblock_crc16_ccitt(buf, len - MESSAGE_TRAILER_SIZE);
buf[len - MESSAGE_TRAILER_CRC] = crc >> 8;
buf[len - MESSAGE_TRAILER_CRC+1] = crc & 0xff;
buf[len - MESSAGE_TRAILER_SYNC] = MESSAGE_SYNC;
// Store message block
if (eventtime > sq->idle_time)
sq->idle_time = eventtime;
sq->idle_time += len * sq->baud_adjust;
struct queue_message *out = message_alloc();
memcpy(out->msg, buf, len);
out->len = len;
out->sent_time = eventtime;
out->receive_time = sq->idle_time;
if (list_empty(&sq->sent_queue))
pollreactor_update_timer(sq->pr, SQPT_RETRANSMIT
, sq->idle_time + sq->rto);
if (!sq->rtt_sample_seq)
sq->rtt_sample_seq = sq->send_seq;
sq->send_seq++;
sq->need_ack_bytes += len;
list_add_tail(&out->node, &sq->sent_queue);
return len;
}
// Determine the time the next serial data should be sent
static double
check_send_command(struct serialqueue *sq, double eventtime)
{
if (sq->send_seq - sq->receive_seq >= MAX_PENDING_BLOCKS
&& sq->receive_seq != (uint64_t)-1)
// Need an ack before more messages can be sent
return PR_NEVER;
if (sq->send_seq > sq->receive_seq && sq->receive_window) {
int need_ack_bytes = sq->need_ack_bytes + MESSAGE_MAX;
if (sq->last_ack_seq < sq->receive_seq)
need_ack_bytes += sq->last_ack_bytes;
if (need_ack_bytes > sq->receive_window)
// Wait for ack from past messages before sending next message
return PR_NEVER;
}
// Check for stalled messages now ready
double idletime = eventtime > sq->idle_time ? eventtime : sq->idle_time;
idletime += MESSAGE_MIN * sq->baud_adjust;
uint64_t ack_clock = clock_from_time(&sq->ce, idletime);
uint64_t min_stalled_clock = MAX_CLOCK, min_ready_clock = MAX_CLOCK;
struct command_queue *cq;
list_for_each_entry(cq, &sq->pending_queues, node) {
// Move messages from the stalled_queue to the ready_queue
while (!list_empty(&cq->stalled_queue)) {
struct queue_message *qm = list_first_entry(
&cq->stalled_queue, struct queue_message, node);
if (ack_clock < qm->min_clock) {
if (qm->min_clock < min_stalled_clock)
min_stalled_clock = qm->min_clock;
break;
}
list_del(&qm->node);
list_add_tail(&qm->node, &cq->ready_queue);
sq->stalled_bytes -= qm->len;
sq->ready_bytes += qm->len;
}
// Update min_ready_clock
if (!list_empty(&cq->ready_queue)) {
struct queue_message *qm = list_first_entry(
&cq->ready_queue, struct queue_message, node);
uint64_t req_clock = qm->req_clock;
double bgoffset = MIN_REQTIME_DELTA + MIN_BACKGROUND_DELTA;
if (req_clock == BACKGROUND_PRIORITY_CLOCK)
req_clock = clock_from_time(&sq->ce, sq->idle_time + bgoffset);
if (req_clock < min_ready_clock)
min_ready_clock = req_clock;
}
}
// Check for messages to send
if (sq->ready_bytes >= MESSAGE_PAYLOAD_MAX)
return PR_NOW;
if (! sq->ce.est_freq) {
if (sq->ready_bytes)
return PR_NOW;
sq->need_kick_clock = MAX_CLOCK;
return PR_NEVER;
}
uint64_t reqclock_delta = MIN_REQTIME_DELTA * sq->ce.est_freq;
if (min_ready_clock <= ack_clock + reqclock_delta)
return PR_NOW;
uint64_t wantclock = min_ready_clock - reqclock_delta;
if (min_stalled_clock < wantclock)
wantclock = min_stalled_clock;
sq->need_kick_clock = wantclock;
return idletime + (wantclock - ack_clock) / sq->ce.est_freq;
}
// Callback timer to send data to the serial port
static double
command_event(struct serialqueue *sq, double eventtime)
{
pthread_mutex_lock(&sq->lock);
uint8_t buf[MESSAGE_MAX * MAX_PENDING_BLOCKS];
int buflen = 0;
double waketime;
for (;;) {
waketime = check_send_command(sq, eventtime);
if (waketime != PR_NOW || buflen + MESSAGE_MAX > sizeof(buf)) {
if (buflen) {
// Write message blocks
do_write(sq, buf, buflen);
sq->bytes_write += buflen;
buflen = 0;
}
if (waketime != PR_NOW)
break;
}
buflen += build_and_send_command(sq, &buf[buflen], eventtime);
}
pthread_mutex_unlock(&sq->lock);
return waketime;
}
// Main background thread for reading/writing to serial port
static void *
background_thread(void *data)
{
struct serialqueue *sq = data;
pollreactor_run(sq->pr);
pthread_mutex_lock(&sq->lock);
check_wake_receive(sq);
pthread_mutex_unlock(&sq->lock);
return NULL;
}
// Create a new 'struct serialqueue' object
struct serialqueue * __visible
serialqueue_alloc(int serial_fd, char serial_fd_type, int client_id)
{
struct serialqueue *sq = malloc(sizeof(*sq));
memset(sq, 0, sizeof(*sq));
sq->serial_fd = serial_fd;
sq->serial_fd_type = serial_fd_type;
sq->client_id = client_id;
int ret = pipe(sq->pipe_fds);
if (ret)
goto fail;
// Reactor setup
sq->pr = pollreactor_alloc(SQPF_NUM, SQPT_NUM, sq);
pollreactor_add_fd(sq->pr, SQPF_SERIAL, serial_fd, input_event
, serial_fd_type==SQT_DEBUGFILE);
pollreactor_add_fd(sq->pr, SQPF_PIPE, sq->pipe_fds[0], kick_event, 0);
pollreactor_add_timer(sq->pr, SQPT_RETRANSMIT, retransmit_event);
pollreactor_add_timer(sq->pr, SQPT_COMMAND, command_event);
fd_set_non_blocking(serial_fd);
fd_set_non_blocking(sq->pipe_fds[0]);
fd_set_non_blocking(sq->pipe_fds[1]);
// Retransmit setup
sq->send_seq = 1;
if (serial_fd_type == SQT_DEBUGFILE) {
// Debug file output
sq->receive_seq = -1;
sq->rto = PR_NEVER;
} else {
sq->receive_seq = 1;
sq->rto = MIN_RTO;
}
// Queues
sq->need_kick_clock = MAX_CLOCK;
list_init(&sq->pending_queues);
list_init(&sq->sent_queue);
list_init(&sq->receive_queue);
list_init(&sq->notify_queue);
list_init(&sq->fast_readers);
// Debugging
list_init(&sq->old_sent);
list_init(&sq->old_receive);
debug_queue_alloc(&sq->old_sent, DEBUG_QUEUE_SENT);
debug_queue_alloc(&sq->old_receive, DEBUG_QUEUE_RECEIVE);
// Thread setup
ret = pthread_mutex_init(&sq->lock, NULL);
if (ret)
goto fail;
ret = pthread_cond_init(&sq->cond, NULL);
if (ret)
goto fail;
ret = pthread_mutex_init(&sq->fast_reader_dispatch_lock, NULL);
if (ret)
goto fail;
ret = pthread_create(&sq->tid, NULL, background_thread, sq);
if (ret)
goto fail;
return sq;
fail:
report_errno("init", ret);
return NULL;
}
// Request that the background thread exit
void __visible
serialqueue_exit(struct serialqueue *sq)
{
pollreactor_do_exit(sq->pr);
kick_bg_thread(sq);
int ret = pthread_join(sq->tid, NULL);
if (ret)
report_errno("pthread_join", ret);
}
// Free all resources associated with a serialqueue
void __visible
serialqueue_free(struct serialqueue *sq)
{
if (!sq)
return;
if (!pollreactor_is_exit(sq->pr))
serialqueue_exit(sq);
pthread_mutex_lock(&sq->lock);
message_queue_free(&sq->sent_queue);
message_queue_free(&sq->receive_queue);
message_queue_free(&sq->notify_queue);
message_queue_free(&sq->old_sent);
message_queue_free(&sq->old_receive);
while (!list_empty(&sq->pending_queues)) {
struct command_queue *cq = list_first_entry(
&sq->pending_queues, struct command_queue, node);
list_del(&cq->node);
message_queue_free(&cq->ready_queue);
message_queue_free(&cq->stalled_queue);
}
pthread_mutex_unlock(&sq->lock);
pollreactor_free(sq->pr);
free(sq);
}
// Allocate a 'struct command_queue'
struct command_queue * __visible
serialqueue_alloc_commandqueue(void)
{
struct command_queue *cq = malloc(sizeof(*cq));
memset(cq, 0, sizeof(*cq));
list_init(&cq->ready_queue);
list_init(&cq->stalled_queue);
return cq;
}
// Free a 'struct command_queue'
void __visible
serialqueue_free_commandqueue(struct command_queue *cq)
{
if (!cq)
return;
if (!list_empty(&cq->ready_queue) || !list_empty(&cq->stalled_queue)) {
errorf("Memory leak! Can't free non-empty commandqueue");
return;
}
free(cq);
}
// Add a low-latency message handler
void
serialqueue_add_fastreader(struct serialqueue *sq, struct fastreader *fr)
{
pthread_mutex_lock(&sq->lock);
list_add_tail(&fr->node, &sq->fast_readers);
pthread_mutex_unlock(&sq->lock);
}
// Remove a previously registered low-latency message handler
void
serialqueue_rm_fastreader(struct serialqueue *sq, struct fastreader *fr)
{
pthread_mutex_lock(&sq->lock);
list_del(&fr->node);
pthread_mutex_unlock(&sq->lock);
pthread_mutex_lock(&sq->fast_reader_dispatch_lock); // XXX - goofy locking
pthread_mutex_unlock(&sq->fast_reader_dispatch_lock);
}
// Add a batch of messages to the given command_queue
void
serialqueue_send_batch(struct serialqueue *sq, struct command_queue *cq
, struct list_head *msgs)
{
// Make sure min_clock is set in list and calculate total bytes
int len = 0;
struct queue_message *qm;
list_for_each_entry(qm, msgs, node) {
if (qm->min_clock + (1LL<<31) < qm->req_clock
&& qm->req_clock != BACKGROUND_PRIORITY_CLOCK)
qm->min_clock = qm->req_clock - (1LL<<31);
len += qm->len;
}
if (! len)
return;
qm = list_first_entry(msgs, struct queue_message, node);
// Add list to cq->stalled_queue
pthread_mutex_lock(&sq->lock);
if (list_empty(&cq->ready_queue) && list_empty(&cq->stalled_queue))
list_add_tail(&cq->node, &sq->pending_queues);
list_join_tail(msgs, &cq->stalled_queue);
sq->stalled_bytes += len;
int mustwake = 0;
if (qm->min_clock < sq->need_kick_clock) {
sq->need_kick_clock = 0;
mustwake = 1;
}
pthread_mutex_unlock(&sq->lock);
// Wake the background thread if necessary
if (mustwake)
kick_bg_thread(sq);
}
// Helper to send a single message
void
serialqueue_send_one(struct serialqueue *sq, struct command_queue *cq
, struct queue_message *qm)
{
struct list_head msgs;
list_init(&msgs);
list_add_tail(&qm->node, &msgs);
serialqueue_send_batch(sq, cq, &msgs);
}
// Schedule the transmission of a message on the serial port at a
// given time and priority.
void __visible
serialqueue_send(struct serialqueue *sq, struct command_queue *cq, uint8_t *msg
, int len, uint64_t min_clock, uint64_t req_clock
, uint64_t notify_id)
{
struct queue_message *qm = message_fill(msg, len);
qm->min_clock = min_clock;
qm->req_clock = req_clock;
qm->notify_id = notify_id;
serialqueue_send_one(sq, cq, qm);
}
// Return a message read from the serial port (or wait for one if none
// available)
void __visible
serialqueue_pull(struct serialqueue *sq, struct pull_queue_message *pqm)
{
pthread_mutex_lock(&sq->lock);
// Wait for message to be available
while (list_empty(&sq->receive_queue)) {
if (pollreactor_is_exit(sq->pr))
goto exit;
sq->receive_waiting = 1;
int ret = pthread_cond_wait(&sq->cond, &sq->lock);
if (ret)
report_errno("pthread_cond_wait", ret);
}
// Remove message from queue
struct queue_message *qm = list_first_entry(
&sq->receive_queue, struct queue_message, node);
list_del(&qm->node);
// Copy message
memcpy(pqm->msg, qm->msg, qm->len);
pqm->len = qm->len;
pqm->sent_time = qm->sent_time;
pqm->receive_time = qm->receive_time;
pqm->notify_id = qm->notify_id;
if (qm->len)
debug_queue_add(&sq->old_receive, qm);
else
message_free(qm);
pthread_mutex_unlock(&sq->lock);
return;
exit:
pqm->len = -1;
pthread_mutex_unlock(&sq->lock);
}
void __visible
serialqueue_set_baud_adjust(struct serialqueue *sq, double baud_adjust)
{
pthread_mutex_lock(&sq->lock);
sq->baud_adjust = baud_adjust;
pthread_mutex_unlock(&sq->lock);
}
void __visible
serialqueue_set_receive_window(struct serialqueue *sq, int receive_window)
{
pthread_mutex_lock(&sq->lock);
sq->receive_window = receive_window;
pthread_mutex_unlock(&sq->lock);
}
// Set the estimated clock rate of the mcu on the other end of the
// serial port
void __visible
serialqueue_set_clock_est(struct serialqueue *sq, double est_freq
, double conv_time, uint64_t conv_clock
, uint64_t last_clock)
{
pthread_mutex_lock(&sq->lock);
sq->ce.est_freq = est_freq;
sq->ce.conv_time = conv_time;
sq->ce.conv_clock = conv_clock;
sq->ce.last_clock = last_clock;
pthread_mutex_unlock(&sq->lock);
}
// Return the latest clock estimate
void
serialqueue_get_clock_est(struct serialqueue *sq, struct clock_estimate *ce)
{
pthread_mutex_lock(&sq->lock);
memcpy(ce, &sq->ce, sizeof(sq->ce));
pthread_mutex_unlock(&sq->lock);
}
// Return a string buffer containing statistics for the serial port
void __visible
serialqueue_get_stats(struct serialqueue *sq, char *buf, int len)
{
struct serialqueue stats;
pthread_mutex_lock(&sq->lock);
memcpy(&stats, sq, sizeof(stats));
pthread_mutex_unlock(&sq->lock);
snprintf(buf, len, "bytes_write=%u bytes_read=%u"
" bytes_retransmit=%u bytes_invalid=%u"
" send_seq=%u receive_seq=%u retransmit_seq=%u"
" srtt=%.3f rttvar=%.3f rto=%.3f"
" ready_bytes=%u stalled_bytes=%u"
, stats.bytes_write, stats.bytes_read
, stats.bytes_retransmit, stats.bytes_invalid
, (int)stats.send_seq, (int)stats.receive_seq
, (int)stats.retransmit_seq
, stats.srtt, stats.rttvar, stats.rto
, stats.ready_bytes, stats.stalled_bytes);
}
// Extract old messages stored in the debug queues
int __visible
serialqueue_extract_old(struct serialqueue *sq, int sentq
, struct pull_queue_message *q, int max)
{
int count = sentq ? DEBUG_QUEUE_SENT : DEBUG_QUEUE_RECEIVE;
struct list_head *rootp = sentq ? &sq->old_sent : &sq->old_receive;
struct list_head replacement, current;
list_init(&replacement);
debug_queue_alloc(&replacement, count);
list_init(&current);
// Atomically replace existing debug list with new zero'd list
pthread_mutex_lock(&sq->lock);
list_join_tail(rootp, &current);
list_init(rootp);
list_join_tail(&replacement, rootp);
pthread_mutex_unlock(&sq->lock);
// Walk the debug list
int pos = 0;
while (!list_empty(&current)) {
struct queue_message *qm = list_first_entry(
&current, struct queue_message, node);
if (qm->len && pos < max) {
struct pull_queue_message *pqm = q++;
pos++;
memcpy(pqm->msg, qm->msg, qm->len);
pqm->len = qm->len;
pqm->sent_time = qm->sent_time;
pqm->receive_time = qm->receive_time;
}
list_del(&qm->node);
message_free(qm);
}
return pos;
}
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