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CLEANUP: mux-h2: add some comments to help understand the code

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Some functions' roles and usage are far from being obvious, and diving
into this part each time requires deep concentration before starting to
understand who does what. Let's add a few comments which help figure
some of the useful pieces.
This commit is contained in:
Willy Tarreau 2019-03-21 19:19:36 +01:00
parent 8ab128c06a
commit 749f5cab83
1 changed files with 35 additions and 6 deletions
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41
src/mux_h2.c
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@ -196,8 +196,8 @@ struct h2s {
unsigned long long body_len; /* remaining body length according to content-length if H2_SF_DATA_CLEN */
struct buffer rxbuf; /* receive buffer, always valid (buf_empty or real buffer) */
struct wait_event wait_event; /* Wait list, when we're attempting to send a RST but we can't send */
struct wait_event *recv_wait; /* Address of the wait_event the conn_stream associated is waiting on */
struct wait_event *send_wait; /* The streeam is waiting for flow control */
struct wait_event *recv_wait; /* recv wait_event the conn_stream associated is waiting on (via h2_subscribe) */
struct wait_event *send_wait; /* send wait_event the conn_stream associated is waiting on (via h2_subscribe) */
struct list list; /* To be used when adding in h2c->send_list or h2c->fctl_lsit */
};
@ -2758,6 +2758,7 @@ schedule:
return sent;
}
/* this is the tasklet referenced in h2c->wait_event.task */
static struct task *h2_io_cb(struct task *t, void *ctx, unsigned short status)
{
struct h2c *h2c = ctx;
@ -2860,6 +2861,7 @@ static int h2_process(struct h2c *h2c)
return 0;
}
/* wake-up function called by the connection layer (mux_ops.wake) */
static int h2_wake(struct connection *conn)
{
struct h2c *h2c = conn->ctx;
@ -3079,6 +3081,9 @@ static void h2_detach(struct conn_stream *cs)
}
}
/* Performs a synchronous or asynchronous shutr().
* FIXME: guess what the return code tries to indicate!
*/
static int h2_do_shutr(struct h2s *h2s)
{
struct h2c *h2c = h2s->h2c;
@ -3130,6 +3135,9 @@ add_to_list:
return 1;
}
/* Performs a synchronous or asynchronous shutw().
* FIXME: guess what the return code tries to indicate!
*/
static int h2_do_shutw(struct h2s *h2s)
{
struct h2c *h2c = h2s->h2c;
@ -3195,6 +3203,10 @@ static int h2_do_shutw(struct h2s *h2s)
return 1;
}
/* This is the tasklet referenced in h2s->wait_event.task, it is used for
* deferred shutdowns when the h2_detach() was done but the mux buffer was full
* and prevented the last frame from being emitted.
*/
static struct task *h2_deferred_shut(struct task *t, void *ctx, unsigned short state)
{
struct h2s *h2s = ctx;
@ -3224,6 +3236,7 @@ static struct task *h2_deferred_shut(struct task *t, void *ctx, unsigned short s
return NULL;
}
/* shutr() called by the conn_stream (mux_ops.shutr) */
static void h2_shutr(struct conn_stream *cs, enum cs_shr_mode mode)
{
struct h2s *h2s = cs->ctx;
@ -3234,6 +3247,7 @@ static void h2_shutr(struct conn_stream *cs, enum cs_shr_mode mode)
h2_do_shutr(h2s);
}
/* shutw() called by the conn_stream (mux_ops.shutw) */
static void h2_shutw(struct conn_stream *cs, enum cs_shw_mode mode)
{
struct h2s *h2s = cs->ctx;
@ -5090,7 +5104,13 @@ static size_t h2s_htx_make_trailers(struct h2s *h2s, struct htx *htx)
goto end;
}
/* Called from the upper layer, to subscribe to events, such as being able to send */
/* Called from the upper layer, to subscribe to events, such as being able to send.
* The <param> argument here is supposed to be a pointer to a wait_event struct
* which will be passed to h2s->recv_wait or h2s->send_wait depending on the
* event_type. The event_type must only be a combination of SUB_RETRY_RECV and
* SUB_RETRY_SEND, other values will lead to -1 being returned. It always
* returns 0 except for the error above.
*/
static int h2_subscribe(struct conn_stream *cs, int event_type, void *param)
{
struct wait_event *sw;
@ -5124,10 +5144,13 @@ static int h2_subscribe(struct conn_stream *cs, int event_type, void *param)
if (event_type != 0)
return -1;
return 0;
}
/* Called from the upper layer, to unsubscribe some events (undo h2_subscribe).
* The <param> argument here is supposed to be a pointer to the same wait_event
* struct that was passed to h2_subscribe() otherwise nothing will be changed.
* It always returns zero.
*/
static int h2_unsubscribe(struct conn_stream *cs, int event_type, void *param)
{
struct wait_event *sw;
@ -5230,6 +5253,9 @@ static size_t h2_rcv_buf(struct conn_stream *cs, struct buffer *buf, size_t coun
return ret;
}
/* stops all senders of this connection for example when the mux buffer is full.
* They are moved from the sending_list to either fctl_list or send_list.
*/
static void h2_stop_senders(struct h2c *h2c)
{
struct h2s *h2s, *h2s_back;
@ -5250,7 +5276,10 @@ static void h2_stop_senders(struct h2c *h2c)
}
}
/* Called from the upper layer, to send data */
/* Called from the upper layer, to send data from buffer <buf> for no more than
* <count> bytes. Returns the number of bytes effectively sent. Some status
* flags may be updated on the conn_stream.
*/
static size_t h2_snd_buf(struct conn_stream *cs, struct buffer *buf, size_t count, int flags)
{
struct h2s *h2s = cs->ctx;