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#include "core.h"
#include <string.h>
#define ACK_RATE 8
#define ACK_MASK_FIRST ((ecp_ack_t)1 << (ECP_RBUF_ACK_SIZE - 1))
static ssize_t msg_store(ECPRBRecv *buf, ecp_seq_t seq, unsigned char *msg, size_t msg_size) {
ssize_t rv = ecp_rbuf_msg_store(&buf->rbuf, seq, msg, msg_size, ECP_RBUF_FLAG_PRESENT, ECP_RBUF_FLAG_PRESENT);
if (rv < 0) return ECP_ERR_RBUF_DUP;
if (ECP_RBUF_SEQ_LT(buf->seq_max, seq)) buf->seq_max = seq;
return rv;
}
static void msg_flush(ECPConnection *conn) {
ECPRBRecv *buf = conn->rbuf.recv;
ecp_seq_t msg_cnt = buf->seq_max - buf->rbuf.seq_start + 1;
ecp_seq_t i = 0;
unsigned int idx = buf->rbuf.msg_start;
for (i=0; i<msg_cnt; i++) {
if (buf->reliable && !(buf->rbuf.msg[idx].flags & ECP_RBUF_FLAG_PRESENT)) break;
if (buf->deliver_delay && msg_cnt - i < buf->deliver_delay) break;
if (buf->rbuf.msg[idx].flags & ECP_RBUF_FLAG_PRESENT) {
buf->rbuf.msg[idx].flags &= ~ECP_RBUF_FLAG_PRESENT;
ecp_msg_handle(conn, buf->rbuf.seq_start + i, buf->rbuf.msg[idx].msg, buf->rbuf.msg[idx].size);
}
idx = ECP_RBUF_IDX_MASK(idx + 1, buf->rbuf.msg_size);
}
buf->rbuf.msg_start = idx;
buf->rbuf.seq_start += i;
}
static int ack_shift(ECPRBRecv *buf) {
int do_ack = 0;
int idx;
int i;
if (buf->reliable && ((buf->ack_map & ACK_MASK_FIRST) == 0)) return 0;
idx = ecp_rbuf_msg_idx(&buf->rbuf, buf->seq_ack);
if (idx < 0) return idx;
while (ECP_RBUF_SEQ_LT(buf->seq_ack, buf->seq_max)) {
idx = ECP_RBUF_IDX_MASK(idx + 1, buf->rbuf.msg_size);
buf->seq_ack++;
if ((buf->rbuf.msg[idx].flags & ECP_RBUF_FLAG_PRESENT) && (buf->ack_map == ECP_RBUF_ACK_FULL)) continue;
buf->ack_map = buf->ack_map << 1;
if (buf->rbuf.msg[idx].flags & ECP_RBUF_FLAG_PRESENT) {
buf->ack_map |= 1;
} else if (!do_ack && ECP_RBUF_SEQ_LTE(buf->seq_ack, buf->seq_max - 2 * buf->hole_max)) {
do_ack = 1;
}
if ((buf->ack_map & ACK_MASK_FIRST) == 0) break;
}
if (!do_ack && (buf->seq_ack == buf->seq_max) && ((buf->ack_map & buf->hole_mask_full) != buf->hole_mask_full)) {
ecp_ack_t hole_mask = buf->ack_map;
for (i=0; i<buf->hole_max-1; i++) {
hole_mask = hole_mask >> 1;
if ((hole_mask & buf->hole_mask_empty) == 0) {
do_ack = 1;
break;
}
}
}
return do_ack;
}
int ecp_rbuf_recv_create(ECPRBRecv *buf, ECPRBMessage *msg, unsigned int msg_size) {
memset(buf, 0, sizeof(ECPRBRecv));
ecp_rbuf_init(&buf->rbuf, msg, msg_size);
buf->ack_map = ECP_RBUF_ACK_FULL;
buf->ack_rate = ACK_RATE;
return ECP_OK;
}
int ecp_rbuf_recv_start(ECPRBRecv *buf, ecp_seq_t seq) {
buf->seq_ack = seq;
buf->seq_max = seq;
buf->rbuf.seq_start = seq + 1;
return ECP_OK;
}
int ecp_rbuf_recv_set_hole(ECPRBRecv *buf, unsigned short hole_max) {
buf->hole_max = hole_max;
buf->hole_mask_full = ~(~((ecp_ack_t)0) << (hole_max * 2));
buf->hole_mask_empty = ~(~((ecp_ack_t)0) << (hole_max + 1));
return ECP_OK;
}
int ecp_rbuf_recv_set_delay(ECPRBRecv *buf, unsigned short delay) {
buf->deliver_delay = delay;
if (buf->hole_max < delay - 1) {
ecp_rbuf_recv_set_hole(buf, delay - 1);
}
return ECP_OK;
}
ssize_t ecp_rbuf_recv_store(ECPConnection *conn, ecp_seq_t seq, unsigned char *msg, size_t msg_size) {
ssize_t rv;
ecp_seq_t ack_pkt = 0;
int do_ack = 0;
ECPRBRecv *buf = conn->rbuf.recv;
if (buf == NULL) return ECP_ERR;
if (ECP_RBUF_SEQ_LT(buf->seq_max, seq)) ack_pkt = seq - buf->seq_max;
if (ECP_RBUF_SEQ_LTE(seq, buf->seq_ack)) {
ecp_seq_t seq_offset = buf->seq_ack - seq;
if (seq_offset < ECP_RBUF_ACK_SIZE) {
ecp_ack_t ack_mask = ((ecp_ack_t)1 << seq_offset);
if (ack_mask & buf->ack_map) return ECP_ERR_RBUF_DUP;
rv = msg_store(buf, seq, msg, msg_size);
if (rv < 0) return rv;
buf->ack_map |= ack_mask;
do_ack = ack_shift(buf);
} else {
return ECP_ERR_RBUF_IDX;
}
} else {
if ((buf->ack_map == ECP_RBUF_ACK_FULL) && (seq == (ecp_seq_t)(buf->seq_ack + 1))) {
if (buf->deliver_delay) {
rv = msg_store(buf, seq, msg, msg_size);
if (rv < 0) return rv;
} else {
rv = ecp_msg_handle(conn, seq, msg, msg_size);
buf->seq_max++;
buf->rbuf.seq_start++;
}
buf->seq_ack++;
} else {
rv = msg_store(buf, seq, msg, msg_size);
if (rv < 0) return rv;
do_ack = ack_shift(buf);
}
}
if (ack_pkt && !do_ack) {
buf->ack_pkt += ack_pkt;
// should send acks more aggresively when reliable and ack_map is not full (rate ~ PPS * RTT)
if (buf->ack_pkt > buf->ack_rate) do_ack = 1;
}
if (do_ack) {
buf->ack_pkt = 0;
// send ack (with seq = 0)
}
// XXX should handle close
msg_flush(conn);
return rv;
}
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