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Memcached_DataObject.php 27.7 KB
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<?php
/*
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 * StatusNet - the distributed open-source microblogging tool
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 * Copyright (C) 2008, 2009, StatusNet, Inc.
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 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

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if (!defined('STATUSNET') && !defined('LACONICA')) { exit(1); }
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class Memcached_DataObject extends Safe_DataObject
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{
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    /**
     * Wrapper for DB_DataObject's static lookup using memcached
     * as backing instead of an in-process cache array.
     *
     * @param string $cls classname of object type to load
     * @param mixed $k key field name, or value for primary key
     * @param mixed $v key field value, or leave out for primary key lookup
     * @return mixed Memcached_DataObject subtype or false
     */
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    function &staticGet($cls, $k, $v=null)
    {
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        if (is_null($v)) {
            $v = $k;
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            // XXX: HACK!
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            $i = new $cls;
            $keys = $i->keys();
            $k = $keys[0];
            unset($i);
        }
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        $i = Memcached_DataObject::getcached($cls, $k, $v);
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        if ($i === false) { // false == cache miss
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            $i = DB_DataObject::factory($cls);
            if (empty($i)) {
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                $i = false;
                return $i;
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            }
            $result = $i->get($k, $v);
            if ($result) {
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                // Hit!
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                $i->encache();
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            } else {
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                // save the fact that no such row exists
                $c = self::memcache();
                if (!empty($c)) {
                    $ck = self::cachekey($cls, $k, $v);
                    $c->set($ck, null);
                }
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                $i = false;
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            }
        }
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        return $i;
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    }
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    /**
     * Get multiple items from the database by key
     * 
     * @param string  $cls       Class to fetch
     * @param string  $keyCol    name of column for key
     * @param array   $keyVals   key values to fetch
     * @param boolean $skipNulls return only non-null results?
     * 
     * @return array Array of objects, in order
     */
    function multiGet($cls, $keyCol, $keyVals, $skipNulls=true)
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    {
    	$result = self::pivotGet($cls, $keyCol, $keyVals);
    	
    	$values = array_values($result);
    	
    	if ($skipNulls) {
    		$tmp = array();
    		foreach ($values as $value) {
    			if (!empty($value)) {
    				$tmp[] = $value;
    			}
    		}
    		$values = $tmp;
    	}
    	
    	return new ArrayWrapper($values);
    }
    
    /**
     * Get multiple items from the database by key
     * 
     * @param string  $cls       Class to fetch
     * @param string  $keyCol    name of column for key
     * @param array   $keyVals   key values to fetch
     * @param boolean $otherCols Other columns to hold fixed
     * 
     * @return array Array mapping $keyVals to objects, or null if not found
     */
    static function pivotGet($cls, $keyCol, $keyVals, $otherCols = array())
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    {
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        if (is_array($keyCol)) {
            foreach ($keyVals as $keyVal) {
                $result[implode(',', $keyVal)] = null;
            }
        } else {
            $result = array_fill_keys($keyVals, null);
        }
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    	$toFetch = array();
    	
    	foreach ($keyVals as $keyVal) {
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            if (is_array($keyCol)) {
                $kv = array_combine($keyCol, $keyVal);
            } else {
                $kv = array($keyCol => $keyVal);
            }

    		$kv = array_merge($otherCols, $kv);
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        	$i = self::multicache($cls, $kv);
        	
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        	if ($i !== false) {
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                if (is_array($keyCol)) {
                    $result[implode(',', $keyVal)] = $i;
                } else {
                    $result[$keyVal] = $i;
                }
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        	} else if (!empty($keyVal)) {
        		$toFetch[] = $keyVal;
        	}
    	}
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    	if (count($toFetch) > 0) {
            $i = DB_DataObject::factory($cls);
            if (empty($i)) {
            	throw new Exception(_('Cannot instantiate class ' . $cls));
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            }
            foreach ($otherCols as $otherKeyCol => $otherKeyVal) {
                $i->$otherKeyCol = $otherKeyVal;
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            }
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            if (is_array($keyCol)) {
                $i->whereAdd(self::_inMultiKey($i, $keyCol, $toFetch));
            } else {
                $i->whereAddIn($keyCol, $toFetch, $i->columnType($keyCol));
            }
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    		if ($i->find()) {
    			while ($i->fetch()) {
    				$copy = clone($i);
    				$copy->encache();
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                    if (is_array($keyCol)) {
                        $vals = array();
                        foreach ($keyCol as $k) {
                            $vals[] = $i->$k;
                        }
                        $result[implode(',', $vals)] = $copy;
                    } else {
                        $result[$i->$keyCol] = $copy;
                    }
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    			}
    		}
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    		// Save state of DB misses
    		
    		foreach ($toFetch as $keyVal) {
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                $r = null;
                if (is_array($keyCol)) {
                    $r = $result[implode(',', $keyVal)];
                } else {
                    $r = $result[$keyVal];
                }
    			if (empty($r)) {
                    if (is_array($keyCol)) {
                        $kv = array_combine($keyCol, $keyVal);
                    } else {
                        $kv = array($keyCol => $keyVal);
                    }
                    $kv = array_merge($otherCols, $kv);
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                	// save the fact that no such row exists
                	$c = self::memcache();
                	if (!empty($c)) {
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                    	$ck = self::multicacheKey($cls, $kv);
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                    	$c->set($ck, null);
                	}	
    			}
    		}
    	}
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    	return $result;
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    }
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    static function _inMultiKey($i, $cols, $values)
    {
        $types = array();

        foreach ($cols as $col) {
            $types[$col] = $i->columnType($col);
        }

        $first = true;

        $query = '';

        foreach ($values as $value) {
            if ($first) {
                $query .= '( ';
                $first = false;
            } else {
                $query .= ' OR ';
            }
            $query .= '( ';
            $i = 0;
            $firstc = true;
            foreach ($cols as $col) {
                if (!$firstc) {
                    $query .= ' AND ';
                } else {
                    $firstc = false;
                }
                switch ($types[$col]) {
                case 'string':
                case 'datetime':
                    $query .= sprintf("%s = %s", $col, $i->_quote($value[$i]));
                    break;
                default:
                    $query .= sprintf("%s = %s", $col, $value[$i]);
                    break;
                }
            }
            $query .= ') ';
        }

        if (!$first) {
            $query .= ' )';
        }

        return $query;
    }

    static function pkeyCols($cls)
    {
        $i = DB_DataObject::factory($cls);
        if (empty($i)) {
            throw new Exception(_('Cannot instantiate a ' . $cls));
        }
        $types = $i->keyTypes();
        ksort($types);

        $pkey = array();

        foreach ($types as $key => $type) {
            if ($type == 'K' || $type == 'N') {
                $pkey[] = $key;
            }
        }

        return $pkey;
    }

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    function listGet($cls, $keyCol, $keyVals)
    {
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    	$pkeyMap = array_fill_keys($keyVals, array());
        $results = array_fill_keys($keyVals, array());

        $pkeyCols = self::pkeyCols($cls);
        
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    	$toFetch = array();
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        $allPkeys = array();

        // We only cache keys -- not objects!

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    	foreach ($keyVals as $keyVal) {
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    	    $l = self::cacheGet(sprintf("%s:list-ids:%s:%s", $cls, $keyCol, $keyVal));
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    	    if ($l !== false) {
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    	        $pkeyMap[$keyVal] = $l;
                $allPkeys = array_merge($allPkeys, $l);
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    	    } else {
    	        $toFetch[] = $keyVal;
    	    }
    	}
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        $keyResults = self::pivotGet($cls, $pkeyCols, $allPkeys);

        foreach ($pkeyMap as $keyVal => $pkeyList) {
            foreach ($pkeyList as $pkeyVal) {
                $i = $keyResults[$pkeyVal];
                if (!empty($i)) {
                    $results[$keyVal][] = $i;
                }
            }
        }

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        if (count($toFetch) > 0) {
	        $i = DB_DataObject::factory($cls);
	        if (empty($i)) {
	        	throw new Exception(_('Cannot instantiate class ' . $cls));
	        }
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            $i->whereAddIn($keyCol, $toFetch, $i->columnType($keyCol));
            if ($i->find()) {
                while ($i->fetch()) {
                    $copy = clone($i);
                    $copy->encache();
                    $result[$i->$keyCol][] = $copy;
                    $pkeyVal = array();
                    foreach ($pkeyCols as $pkeyCol) {
                        $pkeyVal[] = $i->$pkeyCol;
                    }
                    $pkeyMap[$i->$keyCol][] = $pkeyVal;
                }
            }       
	    	foreach ($toFetch as $keyVal) {
                self::cacheSet(sprintf("%s:list-ids:%s:%s", $cls, $keyCol, $keyVal),
                               $pkeyMap[$keyVal]);
            }      
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        }
    	
    	return $result;        
    }
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	function columnType($columnName)
	{
		$keys = $this->table();
		if (!array_key_exists($columnName, $keys)) {
			throw new Exception('Unknown key column ' . $columnName . ' in ' . join(',', array_keys($keys)));
		}
		
		$def = $keys[$columnName];
		
		if ($def & DB_DATAOBJECT_INT) {
			return 'integer';
		} else {
			return 'string';
		}
	}
	
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    /**
     * @fixme Should this return false on lookup fail to match staticGet?
     */
    function pkeyGet($cls, $kv)
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    {
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        $i = Memcached_DataObject::multicache($cls, $kv);
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        if ($i !== false) { // false == cache miss
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            return $i;
        } else {
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            $i = DB_DataObject::factory($cls);
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            if (empty($i) || PEAR::isError($i)) {
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                return false;
            }
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            foreach ($kv as $k => $v) {
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            	if (is_null($v)) {
            		// XXX: possible SQL injection...? Don't 
            		// pass keys from the browser, eh.
            		$i->whereAdd("$k is null");
            	} else {
                	$i->$k = $v;
            	}
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            }
            if ($i->find(true)) {
                $i->encache();
            } else {
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                $i = null;
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                $c = self::memcache();
                if (!empty($c)) {
                    $ck = self::multicacheKey($cls, $kv);
                    $c->set($ck, null);
                }
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            }
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            return $i;
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        }
    }
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    function insert()
    {
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        $result = parent::insert();
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        if ($result) {
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            $this->fixupTimestamps();
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            $this->encache(); // in case of cached negative lookups
        }
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        return $result;
    }
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    function update($orig=null)
    {
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        if (is_object($orig) && $orig instanceof Memcached_DataObject) {
            $orig->decache(); # might be different keys
        }
        $result = parent::update($orig);
        if ($result) {
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            $this->fixupTimestamps();
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            $this->encache();
        }
        return $result;
    }
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    function delete()
    {
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        $this->decache(); # while we still have the values!
        return parent::delete();
    }
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    static function memcache() {
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        return Cache::instance();
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    }
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    static function cacheKey($cls, $k, $v) {
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        if (is_object($cls) || is_object($k) || (is_object($v) && !($v instanceof DB_DataObject_Cast))) {
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            $e = new Exception();
            common_log(LOG_ERR, __METHOD__ . ' object in param: ' .
                str_replace("\n", " ", $e->getTraceAsString()));
        }
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        $vstr = self::valueString($v);
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        return Cache::key(strtolower($cls).':'.$k.':'.$vstr);
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    }
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    static function getcached($cls, $k, $v) {
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        $c = Memcached_DataObject::memcache();
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        if (!$c) {
            return false;
        } else {
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            $obj = $c->get(Memcached_DataObject::cacheKey($cls, $k, $v));
            if (0 == strcasecmp($cls, 'User')) {
                // Special case for User
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                if (is_object($obj) && is_object($obj->id)) {
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                    common_log(LOG_ERR, "User " . $obj->nickname . " was cached with User as ID; deleting");
                    $c->delete(Memcached_DataObject::cacheKey($cls, $k, $v));
                    return false;
                }
            }
            return $obj;
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        }
    }
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    function keyTypes()
    {
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        // ini-based classes return number-indexed arrays. handbuilt
        // classes return column => keytype. Make this uniform.

        $keys = $this->keys();

        $keyskeys = array_keys($keys);

        if (is_string($keyskeys[0])) {
            return $keys;
        }

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        global $_DB_DATAOBJECT;
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        if (!isset($_DB_DATAOBJECT['INI'][$this->_database][$this->__table."__keys"])) {
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            $this->databaseStructure();
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        }
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        return $_DB_DATAOBJECT['INI'][$this->_database][$this->__table."__keys"];
    }
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    function encache()
    {
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        $c = $this->memcache();
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        if (!$c) {
            return false;
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        } else if ($this->tableName() == 'user' && is_object($this->id)) {
            // Special case for User bug
            $e = new Exception();
            common_log(LOG_ERR, __METHOD__ . ' caching user with User object as ID ' .
                       str_replace("\n", " ", $e->getTraceAsString()));
            return false;
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        } else {
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            $keys = $this->_allCacheKeys();
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            foreach ($keys as $key) {
                $c->set($key, $this);
            }
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        }
    }
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    function decache()
    {
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        $c = $this->memcache();
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        if (!$c) {
            return false;
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        }

        $keys = $this->_allCacheKeys();

        foreach ($keys as $key) {
            $c->delete($key, $this);
        }
    }

    function _allCacheKeys()
    {
        $ckeys = array();

        $types = $this->keyTypes();
        ksort($types);

        $pkey = array();
        $pval = array();

        foreach ($types as $key => $type) {

            assert(!empty($key));

            if ($type == 'U') {
                if (empty($this->$key)) {
                    continue;
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                }
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                $ckeys[] = $this->cacheKey($this->tableName(), $key, self::valueString($this->$key));
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            } else if ($type == 'K' || $type == 'N') {
                $pkey[] = $key;
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                $pval[] = self::valueString($this->$key);
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            } else {
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                // Low level exception. No need for i18n as discussed with Brion.
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                throw new Exception("Unknown key type $key => $type for " . $this->tableName());
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            }
        }
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        assert(count($pkey) > 0);

        // XXX: should work for both compound and scalar pkeys
        $pvals = implode(',', $pval);
        $pkeys = implode(',', $pkey);

        $ckeys[] = $this->cacheKey($this->tableName(), $pkeys, $pvals);

        return $ckeys;
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    }
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    function multicache($cls, $kv)
    {
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        ksort($kv);
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        $c = self::memcache();
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        if (!$c) {
            return false;
        } else {
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            return $c->get(self::multicacheKey($cls, $kv));
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        }
    }
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    static function multicacheKey($cls, $kv)
    {
        ksort($kv);
        $pkeys = implode(',', array_keys($kv));
        $pvals = implode(',', array_values($kv));
        return self::cacheKey($cls, $pkeys, $pvals);
    }

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    function getSearchEngine($table)
    {
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        require_once INSTALLDIR.'/lib/search_engines.php';
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        if (Event::handle('GetSearchEngine', array($this, $table, &$search_engine))) {
            if ('mysql' === common_config('db', 'type')) {
                $type = common_config('search', 'type');
                if ($type == 'like') {
                    $search_engine = new MySQLLikeSearch($this, $table);
                } else if ($type == 'fulltext') {
                    $search_engine = new MySQLSearch($this, $table);
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                } else {
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                    // Low level exception. No need for i18n as discussed with Brion.
                    throw new ServerException('Unknown search type: ' . $type);
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                }
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            } else {
                $search_engine = new PGSearch($this, $table);
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            }
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        }
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        return $search_engine;
    }
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    static function cachedQuery($cls, $qry, $expiry=3600)
    {
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        $c = Memcached_DataObject::memcache();
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        if (!$c) {
            $inst = new $cls();
            $inst->query($qry);
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            return $inst;
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        }
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        $key_part = Cache::keyize($cls).':'.md5($qry);
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        $ckey = Cache::key($key_part);
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        $stored = $c->get($ckey);
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        if ($stored !== false) {
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            return new ArrayWrapper($stored);
        }

        $inst = new $cls();
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        $inst->query($qry);
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        $cached = array();
        while ($inst->fetch()) {
            $cached[] = clone($inst);
        }
        $inst->free();
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        $c->set($ckey, $cached, Cache::COMPRESSED, $expiry);
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        return new ArrayWrapper($cached);
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    }
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    /**
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     * sends query to database - this is the private one that must work
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     *   - internal functions use this rather than $this->query()
     *
     * Overridden to do logging.
     *
     * @param  string  $string
     * @access private
     * @return mixed none or PEAR_Error
     */
    function _query($string)
    {
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        if (common_config('db', 'annotate_queries')) {
            $string = $this->annotateQuery($string);
        }

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        $start = microtime(true);
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        $fail = false;
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        $result = null;
        if (Event::handle('StartDBQuery', array($this, $string, &$result))) {
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            common_perf_counter('query', $string);
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            try {
                $result = parent::_query($string);
            } catch (Exception $e) {
                $fail = $e;
            }
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            Event::handle('EndDBQuery', array($this, $string, &$result));
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        }
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        $delta = microtime(true) - $start;

        $limit = common_config('db', 'log_slow_queries');
        if (($limit > 0 && $delta >= $limit) || common_config('db', 'log_queries')) {
            $clean = $this->sanitizeQuery($string);
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            if ($fail) {
                $msg = sprintf("FAILED DB query (%0.3fs): %s - %s", $delta, $fail->getMessage(), $clean);
            } else {
                $msg = sprintf("DB query (%0.3fs): %s", $delta, $clean);
            }
            common_log(LOG_DEBUG, $msg);
        }

        if ($fail) {
            throw $fail;
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        }
        return $result;
    }

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    /**
     * Find the first caller in the stack trace that's not a
     * low-level database function and add a comment to the
     * query string. This should then be visible in process lists
     * and slow query logs, to help identify problem areas.
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     *
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     * Also marks whether this was a web GET/POST or which daemon
     * was running it.
     *
     * @param string $string SQL query string
     * @return string SQL query string, with a comment in it
     */
    function annotateQuery($string)
    {
        $ignore = array('annotateQuery',
                        '_query',
                        'query',
                        'get',
                        'insert',
                        'delete',
                        'update',
                        'find');
        $ignoreStatic = array('staticGet',
                              'pkeyGet',
                              'cachedQuery');
        $here = get_class($this); // if we get confused
        $bt = debug_backtrace();

        // Find the first caller that's not us?
        foreach ($bt as $frame) {
            $func = $frame['function'];
            if (isset($frame['type']) && $frame['type'] == '::') {
                if (in_array($func, $ignoreStatic)) {
                    continue;
                }
                $here = $frame['class'] . '::' . $func;
                break;
            } else if (isset($frame['type']) && $frame['type'] == '->') {
                if ($frame['object'] === $this && in_array($func, $ignore)) {
                    continue;
                }
                if (in_array($func, $ignoreStatic)) {
                    continue; // @fixme this shouldn't be needed?
                }
                $here = get_class($frame['object']) . '->' . $func;
                break;
            }
            $here = $func;
            break;
        }

        if (php_sapi_name() == 'cli') {
            $context = basename($_SERVER['PHP_SELF']);
        } else {
            $context = $_SERVER['REQUEST_METHOD'];
        }

        // Slip the comment in after the first command,
        // or DB_DataObject gets confused about handling inserts and such.
        $parts = explode(' ', $string, 2);
        $parts[0] .= " /* $context $here */";
        return implode(' ', $parts);
    }

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    // Sanitize a query for logging
    // @fixme don't trim spaces in string literals
    function sanitizeQuery($string)
    {
        $string = preg_replace('/\s+/', ' ', $string);
        $string = trim($string);
        return $string;
    }

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    // We overload so that 'SET NAMES "utf8"' is called for
    // each connection

    function _connect()
    {
        global $_DB_DATAOBJECT;
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        $sum = $this->_getDbDsnMD5();

        if (!empty($_DB_DATAOBJECT['CONNECTIONS'][$sum]) &&
            !PEAR::isError($_DB_DATAOBJECT['CONNECTIONS'][$sum])) {
            $exists = true;
        } else {
            $exists = false;
       }

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        // @fixme horrible evil hack!
        //
        // In multisite configuration we don't want to keep around a separate
        // connection for every database; we could end up with thousands of
        // connections open per thread. In an ideal world we might keep
        // a connection per server and select different databases, but that'd
        // be reliant on having the same db username/pass as well.
        //
        // MySQL connections are cheap enough we're going to try just
        // closing out the old connection and reopening when we encounter
        // a new DSN.
        //
        // WARNING WARNING if we end up actually using multiple DBs at a time
        // we'll need some fancier logic here.
755
        if (!$exists && !empty($_DB_DATAOBJECT['CONNECTIONS']) && php_sapi_name() == 'cli') {
756 757 758 759 760 761 762
            foreach ($_DB_DATAOBJECT['CONNECTIONS'] as $index => $conn) {
                if (!empty($conn)) {
                    $conn->disconnect();
                }
                unset($_DB_DATAOBJECT['CONNECTIONS'][$index]);
            }
        }
763

764
        $result = parent::_connect();
765 766

        if ($result && !$exists) {
767
            $DB = &$_DB_DATAOBJECT['CONNECTIONS'][$this->_database_dsn_md5];
768 769 770
            if (common_config('db', 'type') == 'mysql' &&
                common_config('db', 'utf8')) {
                $conn = $DB->connection;
771 772 773 774 775 776
                if (!empty($conn)) {
                    if ($DB instanceof DB_mysqli) {
                        mysqli_set_charset($conn, 'utf8');
                    } else if ($DB instanceof DB_mysql) {
                        mysql_set_charset('utf8', $conn);
                    }
777
                }
778
            }
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            // Needed to make timestamp values usefully comparable.
            if (common_config('db', 'type') == 'mysql') {
                parent::_query("set time_zone='+0:00'");
            }
783
        }
784

785 786
        return $result;
    }
787

788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835
    // XXX: largely cadged from DB_DataObject

    function _getDbDsnMD5()
    {
        if ($this->_database_dsn_md5) {
            return $this->_database_dsn_md5;
        }

        $dsn = $this->_getDbDsn();

        if (is_string($dsn)) {
            $sum = md5($dsn);
        } else {
            /// support array based dsn's
            $sum = md5(serialize($dsn));
        }

        return $sum;
    }

    function _getDbDsn()
    {
        global $_DB_DATAOBJECT;

        if (empty($_DB_DATAOBJECT['CONFIG'])) {
            DB_DataObject::_loadConfig();
        }

        $options = &$_DB_DATAOBJECT['CONFIG'];

        // if the databse dsn dis defined in the object..

        $dsn = isset($this->_database_dsn) ? $this->_database_dsn : null;

        if (!$dsn) {

            if (!$this->_database) {
                $this->_database = isset($options["table_{$this->__table}"]) ? $options["table_{$this->__table}"] : null;
            }

            if ($this->_database && !empty($options["database_{$this->_database}"]))  {
                $dsn = $options["database_{$this->_database}"];
            } else if (!empty($options['database'])) {
                $dsn = $options['database'];
            }
        }

        if (!$dsn) {
836
            // TRANS: Exception thrown when database name or Data Source Name could not be found.
837
            throw new Exception(_("No database name or DSN found anywhere."));
838 839 840 841
        }

        return $dsn;
    }
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    static function blow()
    {
        $c = self::memcache();

        if (empty($c)) {
            return false;
        }

        $args = func_get_args();

        $format = array_shift($args);

        $keyPart = vsprintf($format, $args);

857
        $cacheKey = Cache::key($keyPart);
858 859 860

        return $c->delete($cacheKey);
    }
861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876

    function fixupTimestamps()
    {
        // Fake up timestamp columns
        $columns = $this->table();
        foreach ($columns as $name => $type) {
            if ($type & DB_DATAOBJECT_MYSQLTIMESTAMP) {
                $this->$name = common_sql_now();
            }
        }
    }

    function debugDump()
    {
        common_debug("debugDump: " . common_log_objstring($this));
    }
877 878 879

    function raiseError($message, $type = null, $behaviour = null)
    {
880
        $id = get_class($this);
881
        if (!empty($this->id)) {
882 883
            $id .= ':' . $this->id;
        }
884 885 886
        if ($message instanceof PEAR_Error) {
            $message = $message->getMessage();
        }
887
        // Low level exception. No need for i18n as discussed with Brion.
888
        throw new ServerException("[$id] DB_DataObject error [$type]: $message");
889
    }
890 891 892 893 894 895 896 897 898

    static function cacheGet($keyPart)
    {
        $c = self::memcache();

        if (empty($c)) {
            return false;
        }

899
        $cacheKey = Cache::key($keyPart);
900 901 902 903

        return $c->get($cacheKey);
    }

904
    static function cacheSet($keyPart, $value, $flag=null, $expiry=null)
905 906 907 908 909 910 911
    {
        $c = self::memcache();

        if (empty($c)) {
            return false;
        }

912
        $cacheKey = Cache::key($keyPart);
913

914
        return $c->set($cacheKey, $value, $flag, $expiry);
915
    }
916 917 918 919 920 921 922 923 924 925 926 927 928 929

    static function valueString($v)
    {
        $vstr = null;
        if (is_object($v) && $v instanceof DB_DataObject_Cast) {
            switch ($v->type) {
            case 'date':
                $vstr = $v->year . '-' . $v->month . '-' . $v->day;
                break;
            case 'blob':
            case 'string':
            case 'sql':
            case 'datetime':
            case 'time':
930
                // Low level exception. No need for i18n as discussed with Brion.
931 932 933
                throw new ServerException("Unhandled DB_DataObject_Cast type passed as cacheKey value: '$v->type'");
                break;
            default:
934
                // Low level exception. No need for i18n as discussed with Brion.
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                throw new ServerException("Unknown DB_DataObject_Cast type passed as cacheKey value: '$v->type'");
                break;
            }
        } else {
            $vstr = strval($v);
        }
        return $vstr;
    }
943
}