src/http_htx.o src/buffer.o src/hpack-tbl.o src/shctx.o src/sha1.o \
src/http.o src/hpack-dec.o src/action.o src/proto_udp.o src/http_acl.o \
src/xxhash.o src/hpack-enc.o src/h2.o src/freq_ctr.o src/lru.o \
- src/protocol.o src/arg.o src/hpack-huff.o src/base64.o \
+ src/protocol.o src/arg.o src/hpack-huff.o src/base64.o src/ring.o \
src/hash.o src/mailers.o src/activity.o src/version.o src/trace.o \
src/mworker.o src/mworker-prog.o src/debug.o src/wdt.o src/dict.o \
src/xprt_handshake.o
--- /dev/null
+/*
+ * include/proto/ring.h
+ * This file provides definitions for ring buffers used for disposable data.
+ *
+ * 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
+ */
+
+#ifndef _PROTO_RING_H
+#define _PROTO_RING_H
+
+#include <types/ring.h>
+
+struct ring *ring_new(size_t size);
+struct ring *ring_resize(struct ring *ring, size_t size);
+void ring_free(struct ring *ring);
+
+#endif /* _PROTO_RING_H */
+
+/*
+ * Local variables:
+ * c-indent-level: 8
+ * c-basic-offset: 8
+ * End:
+ */
--- /dev/null
+/*
+ * include/types/ring.h
+ * This file provides definitions for ring buffers used for disposable data.
+ *
+ * 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
+ */
+
+#ifndef _TYPES_RING_H
+#define _TYPES_RING_H
+
+#include <common/buffer.h>
+#include <common/compat.h>
+#include <common/config.h>
+#include <common/ist.h>
+
+/* The code below handles circular buffers with single-producer and multiple
+ * readers (up to 255). The buffer storage area must remain always allocated.
+ * It's made of series of payload blocks followed by a readers count (RC).
+ * There is always a readers count at the beginning of the buffer as well. Each
+ * payload block is composed of a varint-encoded size (VI) followed by the
+ * actual payload (PL).
+ *
+ * The readers count is encoded on a single byte. It indicates how many readers
+ * are still waiting at this position. The writer writes after the buffer's
+ * tail, which initially starts just past the first readers count. Then it
+ * knows by reading this count that it must wake up the readers to indicate
+ * data availability. When a reader reads the payload block, it increments the
+ * next readers count and decrements the current one. The area between the
+ * initial readers count and the next one is protected from overwriting for as
+ * long as the initial count is non-null. As such these readers count are
+ * effective barriers against data recycling.
+ *
+ * Only the writer is allowed to update the buffer's tail/head. This ensures
+ * that events can remain as long as possible so that late readers can get the
+ * maximum history available. It also helps dealing with multi-thread accesses
+ * using a simple RW lock during the buffer head's manipulation. The writer
+ * will have to delete some old records starting at the head until the new
+ * message can fit or a non-null readers count is encountered. If a message
+ * cannot fit due to insufficient room, the message is lost and the drop
+ * counted must be incremented.
+ *
+ * Like any buffer, this buffer naturally wraps at the end and continues at the
+ * beginning. The creation process consists in immediately adding a null
+ * readers count byte into the buffer. The write process consists in always
+ * writing a payload block followed by a new readers count. The delete process
+ * consists in removing a null readers count and payload block. As such, there
+ * is always at least one readers count byte in the buffer available at the
+ * head for new readers to attach to, and one before the tail, both of which
+ * may be the same when the buffer doesn't contain any event. It is thus safe
+ * for any reader to simply keep the absolute offset of the last visited
+ * position and to restart from there. The write will update the buffer's
+ * absolute offset when deleting entries. All this also has the benefit of
+ * allowing a buffer to be hot-resized without losing its contents.
+ *
+ * Thus we have this :
+ * - init of empty buffer:
+ * head-, ,-tail
+ * [ RC | xxxxxxxxxxxxxxxxxxxxxxxxxx ]
+ *
+ * - reader attached:
+ * head-, ,-tail
+ * [ RC | xxxxxxxxxxxxxxxxxxxxxxxxxx ]
+ * ^- +1
+ *
+ * - append of one event:
+ * appended
+ * head-, <----------> ,-tail
+ * [ RC | VI | PL | RC | xxxxxxxxxxx ]
+ *
+ * - reader advancing:
+ * head-, ,-tail
+ * [ RC | VI | PL | RC | xxxxxxxxxxx ]
+ * ^- -1 ^- +1
+ *
+ * - writer removing older message:
+ * head-, ,-tail
+ * [ xxxxxxxxxxxx | RC | xxxxxxxxxxx ]
+ * <---------->
+ * removed
+ */
+
+struct ring {
+ struct buffer buf; // storage area
+ size_t ofs; // absolute offset in history of the buffer's head
+ __decl_hathreads(HA_RWLOCK_T lock);
+ int readers_count;
+};
+
+#endif /* _TYPES_RING_H */
+
+/*
+ * Local variables:
+ * c-indent-level: 8
+ * c-basic-offset: 8
+ * End:
+ */
--- /dev/null
+/*
+ * 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 <stdlib.h>
+#include <common/buf.h>
+#include <common/compat.h>
+#include <common/config.h>
+#include <common/hathreads.h>
+#include <proto/ring.h>
+
+/* Creates and returns a ring buffer of size <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;
+
+ HA_RWLOCK_INIT(&ring->lock);
+ ring->readers_count = 0;
+ ring->ofs = 0;
+ ring->buf = b_make(area, size, 0, 0);
+ /* write the initial RC byte */
+ b_putchr(&ring->buf, 0);
+ return ring;
+ fail:
+ free(area);
+ free(ring);
+ return NULL;
+}
+
+/* Resizes existing ring <ring> to <size> 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(LOGSRV_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;
+ ring->buf.head = 0;
+ }
+
+ HA_RWLOCK_WRUNLOCK(LOGSRV_LOCK, &ring->lock);
+
+ free(area);
+ return ring;
+}
+
+/* destroys and frees ring <ring> */
+void ring_free(struct ring *ring)
+{
+ if (!ring)
+ return;
+ free(ring->buf.area);
+ free(ring);
+}
+
+
+/*
+ * Local variables:
+ * c-indent-level: 8
+ * c-basic-offset: 8
+ * End:
+ */
projects / thirdparty / haproxy.git / commitdiff
