[MEDIUM] introduce pipe pools

A new data type has been added : pipes. Some pre-allocated empty pipes
are maintained in a pool for users such as splice which use them a lot
for very short times.

Pipes are allocated using get_pipe() and released using put_pipe().
Pipes which are released with pending data are immediately killed.
The struct pipe is small (16 to 20 bytes) and may even be further
reduced by unifying ->data and ->next.

It would be nice to have a dedicated cleanup task which would watch
for the pipes usage and destroy a few of them from time to time.

Makefile

@@ -449,7 +449,7 @@ endif
 
 OBJS = src/haproxy.o src/sessionhash.o src/base64.o src/protocols.o \
        src/uri_auth.o src/standard.o src/buffers.o src/log.o src/task.o \
-       src/time.o src/fd.o src/regex.o src/cfgparse.o src/server.o \
+       src/time.o src/fd.o src/pipe.o src/regex.o src/cfgparse.o src/server.o \
        src/checks.o src/queue.o src/client.o src/proxy.o src/proto_uxst.o \
        src/proto_http.o src/stream_sock.o src/appsession.o src/backend.o \
        src/stream_interface.o src/dumpstats.o src/proto_tcp.o \

Makefile.bsd

@@ -100,7 +100,7 @@ LDFLAGS = -g
 
 OBJS = src/haproxy.o src/sessionhash.o src/base64.o src/protocols.o \
        src/uri_auth.o src/standard.o src/buffers.o src/log.o src/task.o \
-       src/time.o src/fd.o src/regex.o src/cfgparse.o src/server.o \
+       src/time.o src/fd.o src/pipe.o src/regex.o src/cfgparse.o src/server.o \
        src/checks.o src/queue.o src/client.o src/proxy.o src/proto_uxst.o \
        src/proto_http.o src/stream_sock.o src/appsession.o src/backend.o \
        src/stream_interface.o src/dumpstats.o src/proto_tcp.o \

Makefile.osx

@@ -97,7 +97,7 @@ LDFLAGS = -g -isysroot /Developer/SDKs/MacOSX10.4u.sdk -arch ppc -arch i386 -mma
 
 OBJS = src/haproxy.o src/sessionhash.o src/base64.o src/protocols.o \
        src/uri_auth.o src/standard.o src/buffers.o src/log.o src/task.o \
-       src/time.o src/fd.o src/regex.o src/cfgparse.o src/server.o \
+       src/time.o src/fd.o src/pipe.o src/regex.o src/cfgparse.o src/server.o \
        src/checks.o src/queue.o src/client.o src/proxy.o src/proto_uxst.o \
        src/proto_http.o src/stream_sock.o src/appsession.o src/backend.o \
        src/stream_interface.o src/dumpstats.o src/proto_tcp.o \

include/proto/pipe.h

@@ -0,0 +1,54 @@
+/*
+  include/proto/pipe.h
+  Pipe management
+
+  Copyright (C) 2000-2009 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_PIPE_H
+#define _PROTO_PIPE_H
+
+#include <common/config.h>
+#include <types/pipe.h>
+
+extern int pipes_used;	/* # of pipes in use (2 fds each) */
+extern int pipes_free;	/* # of pipes unused (2 fds each) */
+
+/* return a pre-allocated empty pipe. Try to allocate one if there isn't any
+ * left. NULL is returned if a pipe could not be allocated.
+ */
+struct pipe *get_pipe();
+
+/* destroy a pipe, possibly because an error was encountered on it. Its FDs
+ * will be closed and it will not be reinjected into the live pool.
+ */
+void kill_pipe(struct pipe *p);
+
+/* put back a unused pipe into the live pool. If it still has data in it, it is
+ * closed and not reinjected into the live pool. The caller is not allowed to
+ * use it once released.
+ */
+void put_pipe(struct pipe *p);
+
+#endif /* _PROTO_PIPE_H */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ */

include/types/pipe.h

@@ -0,0 +1,45 @@
+/*
+  include/types/pipe.h
+  Pipe management.
+
+  Copyright (C) 2000-2009 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_PIPE_H
+#define _TYPES_PIPE_H
+
+#include <common/config.h>
+
+/* A pipe is described by its read and write FDs, and the data remaining in it.
+ * The FDs are valid if there are data pending. The user is not allowed to
+ * change the FDs.
+ */
+struct pipe {
+	int data;	/* number of bytes present in the pipe  */
+	int prod;	/* FD the producer must write to ; -1 if none */
+	int cons;	/* FD the consumer must read from ; -1 if none */
+	struct pipe *next;
+};
+
+#endif /* _TYPES_PIPE_H */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ */

src/pipe.c

@@ -0,0 +1,109 @@
+/*
+ * Pipe management
+ *
+ * Copyright 2000-2009 Willy Tarreau <w@1wt.eu>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ */
+
+#include <unistd.h>
+
+#include <common/config.h>
+#include <common/memory.h>
+
+#include <types/global.h>
+#include <types/pipe.h>
+
+struct pool_head *pool2_pipe = NULL;
+struct pipe *pipes_live = NULL; /* pipes which are still ready to use */
+int pipes_used = 0;             /* # of pipes in use (2 fds each) */
+int pipes_free = 0;             /* # of pipes unused */
+
+/* allocate memory for the pipes */
+static void init_pipe()
+{
+	pool2_pipe = create_pool("pipe", sizeof(struct pipe), MEM_F_SHARED);
+	pipes_used = 0;
+	pipes_free = 0;
+}
+
+/* return a pre-allocated empty pipe. Try to allocate one if there isn't any
+ * left. NULL is returned if a pipe could not be allocated.
+ */
+struct pipe *get_pipe()
+{
+	struct pipe *ret;
+	int pipefd[2];
+
+	if (likely(pipes_live)) {
+		ret = pipes_live;
+		pipes_live = pipes_live->next;
+		pipes_free--;
+		pipes_used++;
+		return ret;
+	}
+
+	if (pipes_used >= global.maxpipes)
+		return NULL;
+
+	ret = pool_alloc2(pool2_pipe);
+	if (!ret)
+		return NULL;
+
+	if (pipe(pipefd) < 0) {
+		pool_free2(pool2_pipe, ret);
+		return NULL;
+	}
+	ret->data = 0;
+	ret->prod = pipefd[1];
+	ret->cons = pipefd[0];
+	ret->next = NULL;
+	pipes_used++;
+	return ret;
+}
+
+/* destroy a pipe, possibly because an error was encountered on it. Its FDs
+ * will be closed and it will not be reinjected into the live pool.
+ */
+void kill_pipe(struct pipe *p)
+{
+	close(p->prod);
+	close(p->cons);
+	pool_free2(pool2_pipe, p);
+	pipes_used--;
+	return;
+}
+
+/* put back a unused pipe into the live pool. If it still has data in it, it is
+ * closed and not reinjected into the live pool. The caller is not allowed to
+ * use it once released.
+ */
+void put_pipe(struct pipe *p)
+{
+	if (p->data) {
+		kill_pipe(p);
+		return;
+	}
+	p->next = pipes_live;
+	pipes_live = p;
+	pipes_free++;
+	pipes_used--;
+}
+
+
+__attribute__((constructor))
+static void __pipe_module_init(void)
+{
+	init_pipe();
+}
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ */