Update of contrib stuff from massimo.

5 files changed, 273 insertions, 0 deletions

diff --git a/contrib/userlock/Makefile b/contrib/userlock/Makefile
new file mode 100644
index 00000000000..0865bde7321
--- /dev/null
+++ b/contrib/userlock/Makefile
@@ -0,0 +1,62 @@
+#-------------------------------------------------------------------------
+#
+# Makefile--
+#    Makefile for new string I/O functions.
+#
+#-------------------------------------------------------------------------
+
+PGDIR = ../..
+SRCDIR = $(PGDIR)/src
+
+include $(SRCDIR)/Makefile.global
+
+INCLUDE_OPT =	-I ./ \
+		-I $(SRCDIR)/ \
+		-I $(SRCDIR)/include \
+		-I $(SRCDIR)/port/$(PORTNAME)
+
+CFLAGS += $(INCLUDE_OPT)
+
+ifeq ($(PORTNAME), linux)
+  ifdef LINUX_ELF
+    ifeq ($(CC), gcc)
+      CFLAGS += -fPIC
+    endif
+  endif
+endif
+
+ifeq ($(PORTNAME), i386_solaris)
+  CFLAGS+= -fPIC
+endif
+
+MODNAME =	user_locks
+
+MODULE =	$(MODNAME)$(DLSUFFIX)
+
+all:		module sql
+
+module:		$(MODULE)
+
+sql:		$(MODNAME).sql
+
+install:	$(MODULE)
+		cp -p $(MODULE) $(LIBDIR)
+		cd $(LIBDIR); strip $(MODULE)
+
+%.sql: %.sql.in
+		sed "s|MODULE_PATHNAME|$(LIBDIR)/$(MODULE)|" < $< > $@
+
+.SUFFIXES: $(DLSUFFIX)
+
+%$(DLSUFFIX): %.c
+		cc $(CFLAGS) -shared -o $@ $<
+
+depend dep:
+		$(CC) -MM $(INCLUDE_OPT) *.c >depend
+
+clean:
+		rm -f $(MODULE) $(MODNAME).sql
+
+ifeq (depend,$(wildcard depend))
+include depend
+endif
diff --git a/contrib/userlock/user_locks.c b/contrib/userlock/user_locks.c
new file mode 100644
index 00000000000..efc9b0a4644
--- /dev/null
+++ b/contrib/userlock/user_locks.c
@@ -0,0 +1,100 @@
+/*
+ * user_locks.c --
+ *
+ * This loadable module, together with my user-lock.patch applied to the
+ * backend, provides support for user-level long-term cooperative locks.
+ *
+ * Copyright (c) 1996, Massimo Dal Zotto <dz@cs.unitn.it>
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "postgres.h"
+#include "miscadmin.h"
+#include "storage/lock.h"
+#include "storage/lmgr.h"
+#include "storage/proc.h"
+#include "storage/block.h"
+#include "storage/multilev.h"
+#include "utils/elog.h"
+
+#include "user_locks.h"
+
+#define USER_LOCKS_TABLE_ID	0
+
+extern Oid MyDatabaseId;
+
+int
+user_lock(unsigned int id1, unsigned int id2, LOCKT lockt)
+{
+    LOCKTAG tag;
+
+    memset(&tag,0,sizeof(LOCKTAG));
+    tag.relId = 0;
+    tag.dbId = MyDatabaseId;
+    tag.tupleId.ip_blkid.bi_hi = id2 >> 16;
+    tag.tupleId.ip_blkid.bi_lo = id2 & 0xffff;
+    tag.tupleId.ip_posid = (unsigned short) (id1 & 0xffff);
+
+    return LockAcquire(USER_LOCKS_TABLE_ID, &tag, lockt);
+}
+
+int
+user_unlock(unsigned int id1, unsigned int id2, LOCKT lockt)
+{
+    LOCKTAG tag;
+
+    memset(&tag, 0,sizeof(LOCKTAG));
+    tag.relId = 0;
+    tag.dbId = MyDatabaseId;
+    tag.tupleId.ip_blkid.bi_hi = id2 >> 16;
+    tag.tupleId.ip_blkid.bi_lo = id2 & 0xffff;
+    tag.tupleId.ip_posid = (unsigned short) (id1 & 0xffff);
+    
+    return LockRelease(USER_LOCKS_TABLE_ID, &tag, lockt);
+}
+
+int
+user_write_lock(unsigned int id1, unsigned int id2)
+{
+    return user_lock(id1, id2, WRITE_LOCK);
+}
+
+
+int
+user_write_unlock(unsigned int id1, unsigned int id2)
+{
+    return user_unlock(id1, id2, WRITE_LOCK);
+}
+
+int
+user_write_lock_oid(Oid oid)
+{
+    return user_lock(0, oid, WRITE_LOCK);
+}
+
+int
+user_write_unlock_oid(Oid oid)
+{
+    return user_unlock(0, oid, WRITE_LOCK);
+}
+
+int
+user_unlock_all()
+{
+    PROC	*proc;
+    SHMEM_OFFSET location;
+
+    ShmemPIDLookup(getpid(),&location);
+    if (location == INVALID_OFFSET) {
+	elog(NOTICE, "UserUnlockAll: unable to get proc ptr");
+	return -1;
+    }
+
+    proc = (PROC *) MAKE_PTR(location);
+    return LockReleaseAll(USER_LOCKS_TABLE_ID, &proc->lockQueue);
+}
+
+/* end of file */
diff --git a/contrib/userlock/user_locks.doc b/contrib/userlock/user_locks.doc
new file mode 100644
index 00000000000..15ffe48f13b
--- /dev/null
+++ b/contrib/userlock/user_locks.doc
@@ -0,0 +1,30 @@
+User locks, by Massimo Dal Zotto <dz@cs.unitn.it>
+
+This loadable module, together with my user-lock.patch applied to the
+backend, provides support for user-level long-term cooperative locks.
+
+For example one can write (this example is written in TclX):
+
+  set rec [sql "select ...,user_write_lock_oid(oid) from table where id=$id"]
+  if {[keylget rec user_write_lock_oid] == 1} {
+      # the write lock has been acquired with the record, start
+      # a long editing session, then update the database and
+      # release the lock.
+      sql "update table set ... where id=$id"
+      sql "select user_write_unlock_oid([keylget rec oid])"
+  } else {
+      # the record has been read but the write lock couldn't be acquired,
+      # so it should not be modified by the application.
+      messageBox "This record is in use by another user, retry later"
+  }
+
+This could also be done by setting a flag in the record itself but in
+this case you have the overhead of the updates to the record and there
+may be some locks not released if the backend or the application crashes
+before resetting the flag.
+It could also be done with a begin/end block but in this case the entire
+table would be locked by postgres and it is not acceptable to do this for
+a long period because other transactions would block completely.
+Note that this type of locks are handled cooperatively by the application
+and do not interfere with the normal locks used by postgres.  So an user
+could still modify an user-locked record if he wanted to ignore the lock.
diff --git a/contrib/userlock/user_locks.h b/contrib/userlock/user_locks.h
new file mode 100644
index 00000000000..ab890483fa4
--- /dev/null
+++ b/contrib/userlock/user_locks.h
@@ -0,0 +1,12 @@
+#ifndef USER_LOCKS_H
+#define USER_LOCKS_H
+
+int user_lock(unsigned int id1, unsigned int id2, LOCKT lockt);
+int user_unlock(unsigned int id1, unsigned int id2, LOCKT lockt);
+int user_write_lock(unsigned int id1, unsigned int id2);
+int user_write_unlock(unsigned int id1, unsigned int id2);
+int user_write_lock_oid(Oid oid);
+int user_write_unlock_oid(Oid oid);
+int user_unlock_all(void);
+
+#endif
diff --git a/contrib/userlock/user_locks.sql.in b/contrib/userlock/user_locks.sql.in
new file mode 100644
index 00000000000..da8d105de9c
--- /dev/null
+++ b/contrib/userlock/user_locks.sql.in
@@ -0,0 +1,69 @@
+-- SQL code to define the user locks functions
+
+-- select user_lock(group,id,type);
+--
+create function user_lock(int4,int4,int4) returns int4
+  as 'MODULE_PATHNAME'
+  language 'c';
+
+-- select user_unlock(group,id,type);
+--
+create function user_unlock(int4,int4,int4) returns int4
+  as 'MODULE_PATHNAME'
+  language 'c';
+
+-- select user_write_lock(group,id);
+--
+create function user_write_lock(int4,int4) returns int4
+  as 'MODULE_PATHNAME'
+  language 'c';
+
+-- select user_write_unlock(group,id);
+--
+create function user_write_unlock(int4,int4) returns int4
+  as 'MODULE_PATHNAME'
+  language 'c';
+
+-- select user_write_lock(group,oid);
+--
+create function user_write_lock(int4,oid) returns int4
+  as 'MODULE_PATHNAME'
+  language 'c';
+
+-- select user_write_unlock(group,oid);
+--
+create function user_write_unlock(int4,oid) returns int4
+  as 'MODULE_PATHNAME'
+  language 'c';
+
+-- select user_write_lock_oid(oid);
+--
+create function user_write_lock_oid(oid) returns int4
+  as 'MODULE_PATHNAME'
+  language 'c';
+
+-- select user_write_unlock_oid(oid);
+--
+create function user_write_unlock_oid(oid) returns int4
+  as 'MODULE_PATHNAME'
+  language 'c';
+
+-- select user_write_lock_oid(int4);
+--
+create function user_write_lock_oid(int4) returns int4
+  as 'MODULE_PATHNAME'
+  language 'c';
+
+-- select user_write_unlock_oid(int4);
+--
+create function user_write_unlock_oid(int4) returns int4
+  as 'MODULE_PATHNAME'
+  language 'c';
+
+-- select user_unlock_all();
+--
+create function user_unlock_all() returns int4
+  as 'MODULE_PATHNAME'
+  language 'c';
+
+-- end of file