libvirt/src/util/virfilecache.h
Daniel P. Berrangé 66ce769d27 qemu: don't continue loading caps if outdated
The XML format used for QEMU capabilities is not required to be
stable across releases, as we invalidate the cache whenever the
libvirt binary changes.

We none the less always try to parse te entire XML file before
we do any validity checks. Thus if we change the format of any
part of the data, or change permitted values for enums, then
libvirtd logs will be spammed with errors.

These are not in fact errors, but an expected scenario.

This change makes the loading code validate the cache timestamp
against the libvirtd timestamp immediately. If they don't match
then we stop loading the rest of the XML file.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2020-06-23 17:33:30 +01:00

140 lines
3.8 KiB
C

/*
* virfilecache.h: file caching for data
*
* Copyright (C) 2017 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, see
* <http://www.gnu.org/licenses/>.
*
*/
#pragma once
#include "internal.h"
#include "virobject.h"
#include "virhash.h"
typedef struct _virFileCache virFileCache;
typedef virFileCache *virFileCachePtr;
/**
* virFileCacheIsValidPtr:
* @data: data object to validate
* @priv: private data created together with cache
*
* Validates the cached data whether it needs to be refreshed
* or no.
*
* Returns *true* if it's valid or *false* if not valid.
*/
typedef bool
(*virFileCacheIsValidPtr)(void *data,
void *priv);
/**
* virFileCacheNewDataPtr:
* @name: name of the new data
* @priv: private data created together with cache
*
* Creates a new data based on the @name. The returned data must be
* an instance of virObject.
*
* Returns data object or NULL on error.
*/
typedef void *
(*virFileCacheNewDataPtr)(const char *name,
void *priv);
/**
* virFileCacheLoadFilePtr:
* @filename: name of a file with cached data
* @name: name of the cached data
* @priv: private data created together with cache
* @outdated: set to true if data was outdated
*
* Loads the cached data from a file @filename. If
* NULL is returned, then @oudated indicates whether
* this was due to the data being outdated, or an
* error loading the cache.
*
* Returns cached data object or NULL on outdated data or error.
*/
typedef void *
(*virFileCacheLoadFilePtr)(const char *filename,
const char *name,
void *priv,
bool *outdated);
/**
* virFileCacheSaveFilePtr:
* @data: data object to save into a file
* @filename: name of the file where to store the cached data
* @priv: private data created together with cache
*
* Stores the cached to a file @filename.
*
* Returns 0 on success, -1 on error.
*/
typedef int
(*virFileCacheSaveFilePtr)(void *data,
const char *filename,
void *priv);
/**
* virFileCachePrivFreePtr:
* @priv: private data created together with cache
*
* This is used to free the private data when the cache object
* is removed.
*/
typedef void
(*virFileCachePrivFreePtr)(void *priv);
typedef struct _virFileCacheHandlers virFileCacheHandlers;
typedef virFileCacheHandlers *virFileCacheHandlersPtr;
struct _virFileCacheHandlers {
virFileCacheIsValidPtr isValid;
virFileCacheNewDataPtr newData;
virFileCacheLoadFilePtr loadFile;
virFileCacheSaveFilePtr saveFile;
virFileCachePrivFreePtr privFree;
};
virFileCachePtr
virFileCacheNew(const char *dir,
const char *suffix,
virFileCacheHandlers *handlers);
void *
virFileCacheLookup(virFileCachePtr cache,
const char *name);
void *
virFileCacheLookupByFunc(virFileCachePtr cache,
virHashSearcher iter,
const void *iterData);
void *
virFileCacheGetPriv(virFileCachePtr cache);
void
virFileCacheSetPriv(virFileCachePtr cache,
void *priv);
int
virFileCacheInsertData(virFileCachePtr cache,
const char *name,
void *data);