[Phplib-commit] CVS: php-lib/php/db/odbc db_sql.inc,1.2,1.3
Brought to you by:
nhruby,
richardarcher
Menu
▾
▴
[Phplib-commit] CVS: php-lib/php/db/odbc db_sql.inc,1.2,1.3
|
From: Richard A. <ric...@us...> - 2001-08-27 07:08:22
|
Update of /cvsroot/phplib/php-lib/php/db/odbc
In directory usw-pr-cvs1:/tmp/cvs-serv23693
Modified Files:
db_sql.inc
Log Message:
Add pseudo-locking and sequence numbers.
Index: db_sql.inc
===================================================================
RCS file: /cvsroot/phplib/php-lib/php/db/odbc/db_sql.inc,v
retrieving revision 1.2
retrieving revision 1.3
diff -C2 -d -r1.2 -r1.3
*** db_sql.inc 2001/08/26 12:13:46 1.2
--- db_sql.inc 2001/08/27 07:08:18 1.3
***************
*** 22,27 ****
var $Halt_On_Error = "yes"; ## "yes" (halt with message), "no" (ignore errors quietly), "report" (ignore errror, but spit a warning)
var $Seq_Table = "db_sequence"; ## Name of the sequence table
! var $Seq_ID_Col = "p_nextid"; ## Name of the Sequence ID column in $Seq_Tab
! var $Seq_Name_Col = "p_seq_name"; ## Name of the Sequence Name column in $Seq_Tab
var $UseODBCCursor = 0; ## Set to 1 to enable execution of stored procedures on the server
--- 22,32 ----
var $Halt_On_Error = "yes"; ## "yes" (halt with message), "no" (ignore errors quietly), "report" (ignore errror, but spit a warning)
var $Seq_Table = "db_sequence"; ## Name of the sequence table
! var $Seq_ID_Col = "p_nextid"; ## Name of the Sequence ID column in $Seq_Table
! var $Seq_Name_Col = "p_seq_name"; ## Name of the Sequence Name column in $Seq_Table
! var $Lock_Table = "db_sequence"; ## Name of the lock table
! var $Lock_Name_Col = "p_seq_name"; ## Name of the lock Name column
! var $Lock_ID_Col = "p_nextid"; ## Name of the lock Name column
! var $Lock_Timeout = 5; ## Wait this long for a lock
! var $Lock_Override = 1; ## Set to 1 to override lock after $Lock_Timeout seconds
var $UseODBCCursor = 0; ## Set to 1 to enable execution of stored procedures on the server
***************
*** 115,119 ****
# $this->Query_Ok = odbc_execute($this->Query_ID);
! $this->Query_ID = odbc_exec($this->Link_ID,$Query_String);
$this->RowCount = -1; # reset num_rows() return value
$this->Row = 0;
--- 120,124 ----
# $this->Query_Ok = odbc_execute($this->Query_ID);
! $this->Query_ID = odbc_exec($this->Link_ID, $Query_String);
$this->RowCount = -1; # reset num_rows() return value
$this->Row = 0;
***************
*** 163,175 ****
}
/* public: table locking */
function lock($table, $mode="write") {
! $this->halt("Does " . $this->type ." have table locking functions?");
! return false;
}
! function unlock() {
! $this->halt("Does " . $this->type ." have table locking functions?");
! return false;
}
--- 168,315 ----
}
+ /* public: get the time in msecs */
+ function getmicrotime() {
+ list($usec, $sec) = explode(" ", microtime());
+ return (float)$usec + (float)$sec;
+ }
+
/* public: table locking */
+ /*
+ ODBC is not guaranteed do table locking natively. This function emulates
+ locking with certain constraints. The intention is to provide at least the
+ minimum functionality required to implement sequences via nextid().
+
+ This function maintains a list of locked tables in a lock table. To lock
+ a table it inserts a row into the lock table with the locked table name
+ suffixed with '_p_lock' as a primary key and with a value of 0.
+ The suffix and value are used so that the sequence table can be used as
+ the lock table if desired.
+ While this row exists a lock will not be granted to another process.
+ To protect against threads failing to release a lock, if a lock is not
+ obtained within $this->Lock_Timeout seconds the lock may be deleted.
+ The timeout value needs to be set to a reasonable length based on the
+ expected transaction time on the locked table.
+
+ This method will only be effective if the locked table is accessed
+ exclusively via this class. This is not a database-enforced lock and
+ there is nothing preventing other applications from modifying a table
+ while it is 'locked'.
+
+ The function uses microtime to prevent multiple threads all hitting the
+ table simultaneously on the tick of a second.
+
+ The function halt()s if a lock cannot be obtained.
+ */
function lock($table, $mode="write") {
!
! if (!$this->connect()) {
! return 0; /* we already complained in connect() about that. */
! };
!
! $getsql = sprintf("INSERT into %s (%s, %s) VALUES ('%s', 0)",
! $this->Lock_Table,
! $this->Lock_Name_Col,
! $this->Lock_ID_Col,
! strtolower($table)."_p_lock");
! $delsql = sprintf("DELETE FROM %s where %s='%s' AND %s=0",
! $this->Lock_Table,
! $this->Lock_Name_Col,
! strtolower($table)."_p_lock",
! $this->Lock_ID_Col);
! $selsql = sprintf("SELECT * FROM %s where %s='%s' AND %s=0",
! $this->Lock_Table,
! $this->Lock_Name_Col,
! strtolower($table)."_p_lock",
! $this->Lock_ID_Col);
! $timeout = $this->getmicrotime() + $this->Lock_Timeout;
! $got_lock = 0;
! $override = $this->Lock_Override;
! while (!$got_lock) {
! $got_lock = @odbc_exec($this->Link_ID, $getsql);
! if ($this->Debug && !$got_lock) {
! echo "missed lock... looping\n";
! flush();
! }
! $currtime = $this->getmicrotime();
! if (!$got_lock) {
! if ($timeout < $currtime) {
! if (!$override) {
! # try to select existing lock
! if (!@odbc_exec($this->Link_ID, $selsql)) {
! # lock select failed. Either the table does not exist or the lock was
! # released just this instant. Try to get a lock to see which...
! $got_lock = @odbc_exec($this->Link_ID, $getsql);
! if (!$got_lock) {
! $this->halt("Lock select failed. Does the table $this->Lock_Table exist?");
! }
! return $got_lock;
! }
! $this->halt("lock() failed.");
! return 0;
! } else {
! # delete existing lock
! if ($this->Debug) {
! echo "overriding lock\n";
! }
!
! if (!@odbc_exec($this->Link_ID, $delsql)) {
! # lock override failed. Either the table does not exist or the lock was
! # released just this instant. Try to get a lock to see which...
! $got_lock = @odbc_exec($this->Link_ID, $getsql);
! if (!$got_lock) {
! $this->halt("Lock override failed. Does the table $this->Lock_Table exist?");
! }
! return $got_lock;
! } else {
! # just deleted the lock so try to get it straight away
! $got_lock = @odbc_exec($this->Link_ID, $getsql);
! $timeout = $currtime + $this->Lock_Timeout; # reset the timer
! $override = 0; # override once only
! # fall through to wait loop
! }
! }
! }
! }
!
! if (!$got_lock) {
! $waittime = $currtime + 0.5;
! while ($waittime > $this->getmicrotime()) {
! ;
! }
! }
! }
! if ($this->Debug && !$got_lock) {
! echo "missed lock... bug!\n";
! } else {
! echo "got lock\n";
! flush();
! }
! return $got_lock;
}
! function unlock($table = "") {
! if (!$this->connect()) {
! return 0; /* we already complained in connect() about that. */
! };
!
! # Note: this unlocks ALL tables if $table is blank!
! if ($table == "") {
! $delsql = sprintf("DELETE FROM %s where %s LIKE '%%_p_lock' AND %s=0",
! $this->Lock_Table,
! $this->Lock_Name_Col,
! $this->Lock_ID_Col);
! } else {
! $delsql = sprintf("DELETE FROM %s where %s='%s' AND %s=0",
! $this->Lock_Table,
! $this->Lock_Name_Col,
! strtolower($table)."_p_lock",
! $this->Lock_ID_Col);
! }
!
! $res = @odbc_exec($this->Link_ID, $delsql);
! if (!$res) {
! $this->halt("unlock() failed.");
! }
! return $res;
}
***************
*** 246,251 ****
/* public: sequence numbers */
function nextid($seq_name) {
! $this->halt("Sequence numbers require locking. Does " . $this->type ." have table locking functions?");
! return false;
}
--- 386,437 ----
/* public: sequence numbers */
function nextid($seq_name) {
! if (!$this->connect()) {
! return 0; /* we already complained in connect() about that. */
! };
!
! if ($this->lock($this->Seq_Table)) {
! /* get sequence number (locked) and increment */
! $q = sprintf("select %s from %s where %s = '%s'",
! $this->Seq_ID_Col,
! $this->Seq_Table,
! $this->Seq_Name_Col,
! $seq_name);
! $id = odbc_exec($this->Link_ID, $q);
! $res = 0;
! if (odbc_fetch_row($id, 1)) {
! $res = array();
! $count = odbc_num_fields($id);
! for ($i=1; $i<=$count; $i++) {
! $res[strtolower(odbc_field_name($id, $i))] = odbc_result($id, $i);
! }
! }
!
! /* No current value, make one */
! if (!is_array($res)) {
! $currentid = 0;
! $q = sprintf("insert into %s ( %s, %s ) values('%s', %s)",
! $this->Seq_Table,
! $this->Seq_Name_Col,
! $this->Seq_ID_Col,
! $seq_name,
! $currentid);
! $id = odbc_exec($this->Link_ID, $q);
! } else {
! $currentid = $res[$this->Seq_ID_Col];
! }
! $nextid = $currentid + 1;
! $q = sprintf("update %s set %s = '%s' where %s = '%s'",
! $this->Seq_Table,
! $this->Seq_ID_Col,
! $nextid,
! $this->Seq_Name_Col,
! $seq_name);
! $id = odbc_exec($this->Link_ID, $q);
! $this->unlock();
! } else {
! $this->halt("cannot lock ".$this->Seq_Table." - has it been created?");
! return 0;
! }
! return $nextid;
}
***************
*** 310,313 ****
--- 496,500 ----
$res["num_fields"] = $count;
+ # ODBC result set starts at 1
for ($i=1; $i<=$count; $i++) {
$res["meta"][$res[$i]["name"]] = $i;
|
