From b46aad6df449445a9fc4aa7b32bd40005438e3f7 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 13 Apr 2024 14:18:05 +0200 Subject: Adding upstream version 2.9.5. Signed-off-by: Daniel Baumann --- src/ring.c | 482 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 482 insertions(+) create mode 100644 src/ring.c (limited to 'src/ring.c') diff --git a/src/ring.c b/src/ring.c new file mode 100644 index 0000000..849221e --- /dev/null +++ b/src/ring.c @@ -0,0 +1,482 @@ +/* + * Ring buffer management + * + * Copyright (C) 2000-2019 Willy Tarreau - w@1wt.eu + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation, version 2.1 + * exclusively. + * + * This library 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 + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* context used to dump the contents of a ring via "show events" or "show errors" */ +struct show_ring_ctx { + struct ring *ring; /* ring to be dumped */ + size_t ofs; /* storage offset to restart from; ~0=oldest */ + uint flags; /* set of RING_WF_* */ +}; + +/* Initialize a pre-allocated ring with the buffer area + * of size */ +void ring_init(struct ring *ring, void *area, size_t size) +{ + HA_RWLOCK_INIT(&ring->lock); + LIST_INIT(&ring->waiters); + ring->readers_count = 0; + ring->buf = b_make(area, size, 0, 0); + /* write the initial RC byte */ + b_putchr(&ring->buf, 0); +} + +/* Creates and returns a ring buffer of size bytes. Returns NULL on + * allocation failure. + */ +struct ring *ring_new(size_t size) +{ + struct ring *ring = NULL; + void *area = NULL; + + if (size < 2) + goto fail; + + ring = malloc(sizeof(*ring)); + if (!ring) + goto fail; + + area = malloc(size); + if (!area) + goto fail; + + ring_init(ring, area, size); + return ring; + fail: + free(area); + free(ring); + return NULL; +} + +/* Creates a unified ring + storage area at address for bytes. + * If is null, then it's allocated of the requested size. The ring + * struct is part of the area so the usable area is slightly reduced. However + * the ring storage is immediately adjacent to the struct. ring_free() will + * ignore such rings, so the caller is responsible for releasing them. + */ +struct ring *ring_make_from_area(void *area, size_t size) +{ + struct ring *ring = NULL; + + if (size < sizeof(*ring)) + return NULL; + + if (!area) + area = malloc(size); + if (!area) + return NULL; + + ring = area; + area += sizeof(*ring); + ring_init(ring, area, size - sizeof(*ring)); + return ring; +} + +/* Cast an unified ring + storage area to a ring from , without + * reinitializing the data buffer. + * + * Reinitialize the waiters and the lock. + */ +struct ring *ring_cast_from_area(void *area) +{ + struct ring *ring = NULL; + + ring = area; + ring->buf.area = area + sizeof(*ring); + + HA_RWLOCK_INIT(&ring->lock); + LIST_INIT(&ring->waiters); + ring->readers_count = 0; + + return ring; +} + +/* Resizes existing ring to which must be larger, without losing + * its contents. The new size must be at least as large as the previous one or + * no change will be performed. The pointer to the ring is returned on success, + * or NULL on allocation failure. This will lock the ring for writes. + */ +struct ring *ring_resize(struct ring *ring, size_t size) +{ + void *area; + + if (b_size(&ring->buf) >= size) + return ring; + + area = malloc(size); + if (!area) + return NULL; + + HA_RWLOCK_WRLOCK(RING_LOCK, &ring->lock); + + /* recheck the buffer's size, it may have changed during the malloc */ + if (b_size(&ring->buf) < size) { + /* copy old contents */ + b_getblk(&ring->buf, area, ring->buf.data, 0); + area = HA_ATOMIC_XCHG(&ring->buf.area, area); + ring->buf.size = size; + } + + HA_RWLOCK_WRUNLOCK(RING_LOCK, &ring->lock); + + free(area); + return ring; +} + +/* destroys and frees ring */ +void ring_free(struct ring *ring) +{ + if (!ring) + return; + + /* make sure it was not allocated by ring_make_from_area */ + if (ring->buf.area == (void *)ring + sizeof(*ring)) + return; + + free(ring->buf.area); + free(ring); +} + +/* Tries to send parts from followed by parts from + * to ring . The message is sent atomically. It may be truncated to + * bytes if is non-null. There is no distinction between the + * two lists, it's just a convenience to help the caller prepend some prefixes + * when necessary. It takes the ring's write lock to make sure no other thread + * will touch the buffer during the update. Returns the number of bytes sent, + * or <=0 on failure. + */ +ssize_t ring_write(struct ring *ring, size_t maxlen, const struct ist pfx[], size_t npfx, const struct ist msg[], size_t nmsg) +{ + struct buffer *buf = &ring->buf; + struct appctx *appctx; + size_t totlen = 0; + size_t lenlen; + uint64_t dellen; + int dellenlen; + ssize_t sent = 0; + int i; + + /* we have to find some room to add our message (the buffer is + * never empty and at least contains the previous counter) and + * to update both the buffer contents and heads at the same + * time (it's doable using atomic ops but not worth the + * trouble, let's just lock). For this we first need to know + * the total message's length. We cannot measure it while + * copying due to the varint encoding of the length. + */ + for (i = 0; i < npfx; i++) + totlen += pfx[i].len; + for (i = 0; i < nmsg; i++) + totlen += msg[i].len; + + if (totlen > maxlen) + totlen = maxlen; + + lenlen = varint_bytes(totlen); + + HA_RWLOCK_WRLOCK(RING_LOCK, &ring->lock); + if (lenlen + totlen + 1 + 1 > b_size(buf)) + goto done_buf; + + while (b_room(buf) < lenlen + totlen + 1) { + /* we need to delete the oldest message (from the end), + * and we have to stop if there's a reader stuck there. + * Unless there's corruption in the buffer it's guaranteed + * that we have enough data to find 1 counter byte, a + * varint-encoded length (1 byte min) and the message + * payload (0 bytes min). + */ + if (*b_head(buf)) + goto done_buf; + dellenlen = b_peek_varint(buf, 1, &dellen); + if (!dellenlen) + goto done_buf; + BUG_ON(b_data(buf) < 1 + dellenlen + dellen); + + b_del(buf, 1 + dellenlen + dellen); + } + + /* OK now we do have room */ + __b_put_varint(buf, totlen); + + totlen = 0; + for (i = 0; i < npfx; i++) { + size_t len = pfx[i].len; + + if (len + totlen > maxlen) + len = maxlen - totlen; + if (len) + __b_putblk(buf, pfx[i].ptr, len); + totlen += len; + } + + for (i = 0; i < nmsg; i++) { + size_t len = msg[i].len; + + if (len + totlen > maxlen) + len = maxlen - totlen; + if (len) + __b_putblk(buf, msg[i].ptr, len); + totlen += len; + } + + *b_tail(buf) = 0; buf->data++; // new read counter + sent = lenlen + totlen + 1; + + /* notify potential readers */ + list_for_each_entry(appctx, &ring->waiters, wait_entry) + appctx_wakeup(appctx); + + done_buf: + HA_RWLOCK_WRUNLOCK(RING_LOCK, &ring->lock); + return sent; +} + +/* Tries to attach appctx as a new reader on ring . This is + * meant to be used by low level appctx code such as CLI or ring forwarding. + * For higher level functions, please see the relevant parts in appctx or CLI. + * It returns non-zero on success or zero on failure if too many users are + * already attached. On success, the caller MUST call ring_detach_appctx() + * to detach itself, even if it was never woken up. + */ +int ring_attach(struct ring *ring) +{ + int users = ring->readers_count; + + do { + if (users >= 255) + return 0; + } while (!_HA_ATOMIC_CAS(&ring->readers_count, &users, users + 1)); + return 1; +} + +/* detach an appctx from a ring. The appctx is expected to be waiting at offset + * relative to the beginning of the storage, or ~0 if not waiting yet. + * Nothing is done if is NULL. + */ +void ring_detach_appctx(struct ring *ring, struct appctx *appctx, size_t ofs) +{ + if (!ring) + return; + + HA_RWLOCK_WRLOCK(RING_LOCK, &ring->lock); + if (ofs != ~0) { + /* reader was still attached */ + if (ofs < b_head_ofs(&ring->buf)) + ofs += b_size(&ring->buf) - b_head_ofs(&ring->buf); + else + ofs -= b_head_ofs(&ring->buf); + + BUG_ON(ofs >= b_size(&ring->buf)); + LIST_DEL_INIT(&appctx->wait_entry); + HA_ATOMIC_DEC(b_peek(&ring->buf, ofs)); + } + HA_ATOMIC_DEC(&ring->readers_count); + HA_RWLOCK_WRUNLOCK(RING_LOCK, &ring->lock); +} + +/* Tries to attach CLI handler as a new reader on ring . This is + * meant to be used when registering a CLI function to dump a buffer, so it + * returns zero on success, or non-zero on failure with a message in the appctx + * CLI context. It automatically sets the io_handler and io_release callbacks if + * they were not set. The take a combination of RING_WF_*. + */ +int ring_attach_cli(struct ring *ring, struct appctx *appctx, uint flags) +{ + struct show_ring_ctx *ctx = applet_reserve_svcctx(appctx, sizeof(*ctx)); + + if (!ring_attach(ring)) + return cli_err(appctx, + "Sorry, too many watchers (255) on this ring buffer. " + "What could it have so interesting to attract so many watchers ?"); + + if (!appctx->io_handler) + appctx->io_handler = cli_io_handler_show_ring; + if (!appctx->io_release) + appctx->io_release = cli_io_release_show_ring; + + memset(ctx, 0, sizeof(*ctx)); + ctx->ring = ring; + ctx->ofs = ~0; // start from the oldest event + ctx->flags = flags; + return 0; +} + +/* This function dumps all events from the ring whose pointer is in into + * the appctx's output buffer, and takes from the seek offset into the + * buffer's history (0 for oldest known event). It looks at for boolean + * options: bit0 means it must wait for new data or any key to be pressed. Bit1 + * means it must seek directly to the end to wait for new contents. It returns + * 0 if the output buffer or events are missing is full and it needs to be + * called again, otherwise non-zero. It is meant to be used with + * cli_release_show_ring() to clean up. + */ +int cli_io_handler_show_ring(struct appctx *appctx) +{ + struct show_ring_ctx *ctx = appctx->svcctx; + struct stconn *sc = appctx_sc(appctx); + struct ring *ring = ctx->ring; + struct buffer *buf = &ring->buf; + size_t ofs; + size_t last_ofs; + uint64_t msg_len; + size_t len, cnt; + int ret; + + /* FIXME: Don't watch the other side !*/ + if (unlikely(sc_opposite(sc)->flags & SC_FL_SHUT_DONE)) + return 1; + + HA_RWLOCK_WRLOCK(RING_LOCK, &ring->lock); + LIST_DEL_INIT(&appctx->wait_entry); + HA_RWLOCK_WRUNLOCK(RING_LOCK, &ring->lock); + + HA_RWLOCK_RDLOCK(RING_LOCK, &ring->lock); + + /* explanation for the initialization below: it would be better to do + * this in the parsing function but this would occasionally result in + * dropped events because we'd take a reference on the oldest message + * and keep it while being scheduled. Thus instead let's take it the + * first time we enter here so that we have a chance to pass many + * existing messages before grabbing a reference to a location. This + * value cannot be produced after initialization. + */ + if (unlikely(ctx->ofs == ~0)) { + /* going to the end means looking at tail-1 */ + ctx->ofs = b_peek_ofs(buf, (ctx->flags & RING_WF_SEEK_NEW) ? b_data(buf) - 1 : 0); + HA_ATOMIC_INC(b_orig(buf) + ctx->ofs); + } + + /* we were already there, adjust the offset to be relative to + * the buffer's head and remove us from the counter. + */ + ofs = ctx->ofs - b_head_ofs(buf); + if (ctx->ofs < b_head_ofs(buf)) + ofs += b_size(buf); + + BUG_ON(ofs >= buf->size); + HA_ATOMIC_DEC(b_peek(buf, ofs)); + + /* in this loop, ofs always points to the counter byte that precedes + * the message so that we can take our reference there if we have to + * stop before the end (ret=0). + */ + ret = 1; + while (ofs + 1 < b_data(buf)) { + cnt = 1; + len = b_peek_varint(buf, ofs + cnt, &msg_len); + if (!len) + break; + cnt += len; + BUG_ON(msg_len + ofs + cnt + 1 > b_data(buf)); + + if (unlikely(msg_len + 1 > b_size(&trash))) { + /* too large a message to ever fit, let's skip it */ + ofs += cnt + msg_len; + continue; + } + + chunk_reset(&trash); + len = b_getblk(buf, trash.area, msg_len, ofs + cnt); + trash.data += len; + trash.area[trash.data++] = '\n'; + + if (applet_putchk(appctx, &trash) == -1) { + ret = 0; + break; + } + ofs += cnt + msg_len; + } + + HA_ATOMIC_INC(b_peek(buf, ofs)); + last_ofs = b_tail_ofs(buf); + ctx->ofs = b_peek_ofs(buf, ofs); + HA_RWLOCK_RDUNLOCK(RING_LOCK, &ring->lock); + + if (ret && (ctx->flags & RING_WF_WAIT_MODE)) { + /* we've drained everything and are configured to wait for more + * data or an event (keypress, close) + */ + if (!sc_oc(sc)->output && !(sc->flags & SC_FL_SHUT_DONE)) { + /* let's be woken up once new data arrive */ + HA_RWLOCK_WRLOCK(RING_LOCK, &ring->lock); + LIST_APPEND(&ring->waiters, &appctx->wait_entry); + ofs = b_tail_ofs(&ring->buf); + HA_RWLOCK_WRUNLOCK(RING_LOCK, &ring->lock); + if (ofs != last_ofs) { + /* more data was added into the ring between the + * unlock and the lock, and the writer might not + * have seen us. We need to reschedule a read. + */ + applet_have_more_data(appctx); + } else + applet_have_no_more_data(appctx); + ret = 0; + } + /* always drain all the request */ + co_skip(sc_oc(sc), sc_oc(sc)->output); + } + + applet_expect_no_data(appctx); + return ret; +} + +/* must be called after cli_io_handler_show_ring() above */ +void cli_io_release_show_ring(struct appctx *appctx) +{ + struct show_ring_ctx *ctx = appctx->svcctx; + struct ring *ring = ctx->ring; + size_t ofs = ctx->ofs; + + ring_detach_appctx(ring, appctx, ofs); +} + +/* Returns the MAXIMUM payload len that could theoretically fit into the ring + * based on ring buffer size. + * + * Computation logic relies on implementation details from 'ring-t.h'. + */ +size_t ring_max_payload(const struct ring *ring) +{ + size_t max; + + /* initial max = bufsize - 1 (initial RC) - 1 (payload RC) */ + max = b_size(&ring->buf) - 1 - 1; + + /* subtract payload VI (varint-encoded size) */ + max -= varint_bytes(max); + return max; +} + +/* + * Local variables: + * c-indent-level: 8 + * c-basic-offset: 8 + * End: + */ -- cgit v1.2.3