libvirt/src/datatypes.h
Daniel P. Berrange 2ff4c13754 Remove all object hashtable caches from virConnectPtr
The virConnectPtr struct will cache instances of all other
objects. APIs like virDomainLookupByUUID will return a
cached object, so if you do virDomainLookupByUUID twice in
a row, you'll get the same exact virDomainPtr instance.

This does not have any performance benefit, since the actual
logic in virDomainLookupByUUID (and other APIs returning
virDomainPtr, etc instances) is not short-circuited. All
it does is to ensure there is only one single virDomainPtr
in existance for any given UUID.

The caching has a number of downsides though, all relating
to stale data. If APIs aren't careful to always overwrite
the 'id' field in virDomainPtr it may become out of data.
Likewise for the name field, if a guest is renamed, or if
a guest is deleted, and then a new one created with the
same UUID but different name.

This has been an ongoing, endless source of bugs for all
applications using libvirt from languages with garbage
collection, causing them to get virDomainPtr instances
from long ago with stale data.

The caching is also a waste of memory resources, since
both applications, and language bindings often maintain
their own hashtable caches of object instances.

This patch removes all the hash table caching, so all
APIs return brand new virDomainPtr (etc) object instances.

* src/datatypes.h: Delete all hash tables.
* src/datatypes.c: Remove all object caching code
2011-02-21 11:50:46 +00:00

387 lines
13 KiB
C

/*
* datatypes.h: management of structs for public data types
*
* Copyright (C) 2006-2008, 2010 Red Hat, Inc.
*
* 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; either
* version 2.1 of the License, or (at your option) any later version.
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#ifndef __VIRT_DATATYPES_H_
# define __VIRT_DATATYPES_H_
# include "internal.h"
# include "driver.h"
# include "threads.h"
/**
* VIR_CONNECT_MAGIC:
*
* magic value used to protect the API when pointers to connection structures
* are passed down by the uers.
*/
# define VIR_CONNECT_MAGIC 0x4F23DEAD
# define VIR_IS_CONNECT(obj) ((obj) && (obj)->magic==VIR_CONNECT_MAGIC)
/**
* VIR_DOMAIN_MAGIC:
*
* magic value used to protect the API when pointers to domain structures
* are passed down by the users.
*/
# define VIR_DOMAIN_MAGIC 0xDEAD4321
# define VIR_IS_DOMAIN(obj) ((obj) && (obj)->magic==VIR_DOMAIN_MAGIC)
# define VIR_IS_CONNECTED_DOMAIN(obj) (VIR_IS_DOMAIN(obj) && VIR_IS_CONNECT((obj)->conn))
/**
* VIR_NETWORK_MAGIC:
*
* magic value used to protect the API when pointers to network structures
* are passed down by the users.
*/
# define VIR_NETWORK_MAGIC 0xDEAD1234
# define VIR_IS_NETWORK(obj) ((obj) && (obj)->magic==VIR_NETWORK_MAGIC)
# define VIR_IS_CONNECTED_NETWORK(obj) (VIR_IS_NETWORK(obj) && VIR_IS_CONNECT((obj)->conn))
/**
* VIR_INTERFACE_MAGIC:
*
* magic value used to protect the API when pointers to interface structures
* are passed down by the users.
*/
# define VIR_INTERFACE_MAGIC 0xDEAD5309
# define VIR_IS_INTERFACE(obj) ((obj) && (obj)->magic==VIR_INTERFACE_MAGIC)
# define VIR_IS_CONNECTED_INTERFACE(obj) (VIR_IS_INTERFACE(obj) && VIR_IS_CONNECT((obj)->conn))
/**
* VIR_STORAGE_POOL_MAGIC:
*
* magic value used to protect the API when pointers to storage pool structures
* are passed down by the users.
*/
# define VIR_STORAGE_POOL_MAGIC 0xDEAD5678
# define VIR_IS_STORAGE_POOL(obj) ((obj) && (obj)->magic==VIR_STORAGE_POOL_MAGIC)
# define VIR_IS_CONNECTED_STORAGE_POOL(obj) (VIR_IS_STORAGE_POOL(obj) && VIR_IS_CONNECT((obj)->conn))
/**
* VIR_STORAGE_VOL_MAGIC:
*
* magic value used to protect the API when pointers to storage vol structures
* are passed down by the users.
*/
# define VIR_STORAGE_VOL_MAGIC 0xDEAD8765
# define VIR_IS_STORAGE_VOL(obj) ((obj) && (obj)->magic==VIR_STORAGE_VOL_MAGIC)
# define VIR_IS_CONNECTED_STORAGE_VOL(obj) (VIR_IS_STORAGE_VOL(obj) && VIR_IS_CONNECT((obj)->conn))
/**
* VIR_NODE_DEVICE_MAGIC:
*
* magic value used to protect the API when pointers to storage vol structures
* are passed down by the users.
*/
# define VIR_NODE_DEVICE_MAGIC 0xDEAD5679
# define VIR_IS_NODE_DEVICE(obj) ((obj) && (obj)->magic==VIR_NODE_DEVICE_MAGIC)
# define VIR_IS_CONNECTED_NODE_DEVICE(obj) (VIR_IS_NODE_DEVICE(obj) && VIR_IS_CONNECT((obj)->conn))
/**
* VIR_SECRET_MAGIC:
*
* magic value used to protect the API when pointers to secret structures are
* passed down by the users.
*/
# define VIR_SECRET_MAGIC 0x5678DEAD
# define VIR_IS_SECRET(obj) ((obj) && (obj)->magic==VIR_SECRET_MAGIC)
# define VIR_IS_CONNECTED_SECRET(obj) (VIR_IS_SECRET(obj) && VIR_IS_CONNECT((obj)->conn))
/**
* VIR_STREAM_MAGIC:
*
* magic value used to protect the API when pointers to stream structures
* are passed down by the users.
*/
# define VIR_STREAM_MAGIC 0x1DEAD666
# define VIR_IS_STREAM(obj) ((obj) && (obj)->magic==VIR_STREAM_MAGIC)
# define VIR_IS_CONNECTED_STREAM(obj) (VIR_IS_STREAM(obj) && VIR_IS_CONNECT((obj)->conn))
/**
* VIR_NWFILTER_MAGIC:
*
* magic value used to protect the API when pointers to network filter
* pool structures are passed down by the users.
*/
# define VIR_NWFILTER_MAGIC 0xDEAD7777
# define VIR_IS_NWFILTER(obj) ((obj) && (obj)->magic==VIR_NWFILTER_MAGIC)
# define VIR_IS_CONNECTED_NWFILTER(obj) (VIR_IS_NWFILTER(obj) && VIR_IS_CONNECT((obj)->conn))
/**
* VIR_SNAPSHOT_MAGIC:
*
* magic value used to protect the API when pointers to snapshot structures
* are passed down by the users.
*/
# define VIR_SNAPSHOT_MAGIC 0x6666DEAD
# define VIR_IS_SNAPSHOT(obj) ((obj) && (obj)->magic==VIR_SNAPSHOT_MAGIC)
# define VIR_IS_DOMAIN_SNAPSHOT(obj) (VIR_IS_SNAPSHOT(obj) && VIR_IS_DOMAIN((obj)->domain))
/**
* _virConnect:
*
* Internal structure associated to a connection
*/
struct _virConnect {
/* All the variables from here, until the 'lock' declaration
* are setup at time of connection open, and never changed
* since. Thus no need to lock when accessing them
*/
unsigned int magic; /* specific value to check */
int flags; /* a set of connection flags */
xmlURIPtr uri; /* connection URI */
/* The underlying hypervisor driver and network driver. */
virDriverPtr driver;
virNetworkDriverPtr networkDriver;
virInterfaceDriverPtr interfaceDriver;
virStorageDriverPtr storageDriver;
virDeviceMonitorPtr deviceMonitor;
virSecretDriverPtr secretDriver;
virNWFilterDriverPtr nwfilterDriver;
/* Private data pointer which can be used by driver and
* network driver as they wish.
* NB: 'private' is a reserved word in C++.
*/
void * privateData;
void * networkPrivateData;
void * interfacePrivateData;
void * storagePrivateData;
void * devMonPrivateData;
void * secretPrivateData;
void * nwfilterPrivateData;
/*
* The lock mutex must be acquired before accessing/changing
* any of members following this point, or changing the ref
* count of any virDomain/virNetwork object associated with
* this connection
*/
virMutex lock;
/* Per-connection error. */
virError err; /* the last error */
virErrorFunc handler; /* associated handlet */
void *userData; /* the user data */
int refs; /* reference count */
};
/**
* _virDomain:
*
* Internal structure associated to a domain
*/
struct _virDomain {
unsigned int magic; /* specific value to check */
int refs; /* reference count */
virConnectPtr conn; /* pointer back to the connection */
char *name; /* the domain external name */
int id; /* the domain ID */
unsigned char uuid[VIR_UUID_BUFLEN]; /* the domain unique identifier */
};
/**
* _virNetwork:
*
* Internal structure associated to a domain
*/
struct _virNetwork {
unsigned int magic; /* specific value to check */
int refs; /* reference count */
virConnectPtr conn; /* pointer back to the connection */
char *name; /* the network external name */
unsigned char uuid[VIR_UUID_BUFLEN]; /* the network unique identifier */
};
/**
* _virInterface:
*
* Internal structure associated to a physical host interface
*/
struct _virInterface {
unsigned int magic; /* specific value to check */
int refs; /* reference count */
virConnectPtr conn; /* pointer back to the connection */
char *name; /* the network external name */
char *mac; /* the interface MAC address */
};
/**
* _virStoragePool:
*
* Internal structure associated to a storage pool
*/
struct _virStoragePool {
unsigned int magic; /* specific value to check */
int refs; /* reference count */
virConnectPtr conn; /* pointer back to the connection */
char *name; /* the storage pool external name */
unsigned char uuid[VIR_UUID_BUFLEN]; /* the storage pool unique identifier */
};
/**
* _virStorageVol:
*
* Internal structure associated to a storage volume
*/
struct _virStorageVol {
unsigned int magic; /* specific value to check */
int refs; /* reference count */
virConnectPtr conn; /* pointer back to the connection */
char *pool; /* Pool name of owner */
char *name; /* the storage vol external name */
/* XXX currently abusing path for this. Ought not to be so evil */
char key[PATH_MAX]; /* unique key for storage vol */
};
/**
* _virNodeDevice:
*
* Internal structure associated with a node device
*/
struct _virNodeDevice {
unsigned int magic; /* specific value to check */
int refs; /* reference count */
virConnectPtr conn; /* pointer back to the connection */
char *name; /* device name (unique on node) */
char *parent; /* parent device name */
};
/**
* _virSecret:
*
* Internal structure associated with a secret
*/
struct _virSecret {
unsigned int magic; /* specific value to check */
int refs; /* reference count */
virConnectPtr conn; /* pointer back to the connection */
unsigned char uuid[VIR_UUID_BUFLEN]; /* the domain unique identifier */
int usageType; /* the type of usage */
char *usageID; /* the usage's unique identifier */
};
typedef int (*virStreamAbortFunc)(virStreamPtr, void *opaque);
typedef int (*virStreamFinishFunc)(virStreamPtr, void *opaque);
/**
* _virStream:
*
* Internal structure associated with an input stream
*/
struct _virStream {
unsigned int magic;
virConnectPtr conn;
int refs;
int flags;
virStreamDriverPtr driver;
void *privateData;
};
/**
* _virDomainSnapshot
*
* Internal structure associated with a domain snapshot
*/
struct _virDomainSnapshot {
unsigned int magic;
int refs;
char *name;
virDomainPtr domain;
};
/************************************************************************
* *
* API for domain/connections (de)allocations and lookups *
* *
************************************************************************/
virConnectPtr virGetConnect(void);
int virUnrefConnect(virConnectPtr conn);
virDomainPtr virGetDomain(virConnectPtr conn,
const char *name,
const unsigned char *uuid);
int virUnrefDomain(virDomainPtr domain);
virNetworkPtr virGetNetwork(virConnectPtr conn,
const char *name,
const unsigned char *uuid);
int virUnrefNetwork(virNetworkPtr network);
virInterfacePtr virGetInterface(virConnectPtr conn,
const char *name,
const char *mac);
int virUnrefInterface(virInterfacePtr iface);
virStoragePoolPtr virGetStoragePool(virConnectPtr conn,
const char *name,
const unsigned char *uuid);
int virUnrefStoragePool(virStoragePoolPtr pool);
virStorageVolPtr virGetStorageVol(virConnectPtr conn,
const char *pool,
const char *name,
const char *key);
int virUnrefStorageVol(virStorageVolPtr vol);
virNodeDevicePtr virGetNodeDevice(virConnectPtr conn,
const char *name);
int virUnrefNodeDevice(virNodeDevicePtr dev);
virSecretPtr virGetSecret(virConnectPtr conn,
const unsigned char *uuid,
int usageType,
const char *usageID);
int virUnrefSecret(virSecretPtr secret);
virStreamPtr virGetStream(virConnectPtr conn);
int virUnrefStream(virStreamPtr st);
/**
* _virNWFilter:
*
* Internal structure associated to a network filter
*/
struct _virNWFilter {
unsigned int magic; /* specific value to check */
int refs; /* reference count */
virConnectPtr conn; /* pointer back to the connection */
char *name; /* the network filter external name */
unsigned char uuid[VIR_UUID_BUFLEN]; /* the network filter unique identifier */
};
virNWFilterPtr virGetNWFilter(virConnectPtr conn,
const char *name,
const unsigned char *uuid);
int virUnrefNWFilter(virNWFilterPtr nwfilter);
virDomainSnapshotPtr virGetDomainSnapshot(virDomainPtr domain,
const char *name);
int virUnrefDomainSnapshot(virDomainSnapshotPtr snapshot);
#endif