gecko/netwerk/cache/nsDiskCacheBinding.cpp
2011-10-17 10:59:28 -04:00

395 lines
12 KiB
C++

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is nsDiskCacheBinding.cpp, released
* May 10, 2001.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 2001
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Patrick C. Beard <beard@netscape.com>
* Gordon Sheridan <gordon@netscape.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#include <limits.h>
#include "nscore.h"
#include "nsDiskCacheBinding.h"
/******************************************************************************
* static hash table callback functions
*
*****************************************************************************/
struct HashTableEntry : PLDHashEntryHdr {
nsDiskCacheBinding * mBinding;
};
static PLDHashNumber
HashKey( PLDHashTable *table, const void *key)
{
return (PLDHashNumber) NS_PTR_TO_INT32(key);
}
static bool
MatchEntry(PLDHashTable * /* table */,
const PLDHashEntryHdr * header,
const void * key)
{
HashTableEntry * hashEntry = (HashTableEntry *) header;
return (hashEntry->mBinding->mRecord.HashNumber() == (PLDHashNumber) NS_PTR_TO_INT32(key));
}
static void
MoveEntry(PLDHashTable * /* table */,
const PLDHashEntryHdr * src,
PLDHashEntryHdr * dst)
{
((HashTableEntry *)dst)->mBinding = ((HashTableEntry *)src)->mBinding;
}
static void
ClearEntry(PLDHashTable * /* table */,
PLDHashEntryHdr * header)
{
((HashTableEntry *)header)->mBinding = nsnull;
}
/******************************************************************************
* Utility Functions
*****************************************************************************/
nsDiskCacheBinding *
GetCacheEntryBinding(nsCacheEntry * entry)
{
return (nsDiskCacheBinding *) entry->Data();
}
/******************************************************************************
* nsDiskCacheBinding
*****************************************************************************/
NS_IMPL_THREADSAFE_ISUPPORTS0(nsDiskCacheBinding)
nsDiskCacheBinding::nsDiskCacheBinding(nsCacheEntry* entry, nsDiskCacheRecord * record)
: mCacheEntry(entry)
, mStreamIO(nsnull)
, mDeactivateEvent(nsnull)
{
NS_ASSERTION(record->ValidRecord(), "bad record");
PR_INIT_CLIST(this);
mRecord = *record;
mDoomed = entry->IsDoomed();
mGeneration = record->Generation(); // 0 == uninitialized, or data & meta using block files
}
nsDiskCacheBinding::~nsDiskCacheBinding()
{
NS_ASSERTION(PR_CLIST_IS_EMPTY(this), "binding deleted while still on list");
if (!PR_CLIST_IS_EMPTY(this))
PR_REMOVE_LINK(this); // XXX why are we still on a list?
// sever streamIO/binding link
if (mStreamIO) {
mStreamIO->ClearBinding();
NS_RELEASE(mStreamIO);
}
}
nsresult
nsDiskCacheBinding::EnsureStreamIO()
{
if (!mStreamIO) {
mStreamIO = new nsDiskCacheStreamIO(this);
if (!mStreamIO) return NS_ERROR_OUT_OF_MEMORY;
NS_ADDREF(mStreamIO);
}
return NS_OK;
}
/******************************************************************************
* nsDiskCacheBindery
*
* Keeps track of bound disk cache entries to detect for collisions.
*
*****************************************************************************/
PLDHashTableOps nsDiskCacheBindery::ops =
{
PL_DHashAllocTable,
PL_DHashFreeTable,
HashKey,
MatchEntry,
MoveEntry,
ClearEntry,
PL_DHashFinalizeStub
};
nsDiskCacheBindery::nsDiskCacheBindery()
: initialized(false)
{
}
nsDiskCacheBindery::~nsDiskCacheBindery()
{
Reset();
}
nsresult
nsDiskCacheBindery::Init()
{
nsresult rv = NS_OK;
initialized = PL_DHashTableInit(&table, &ops, nsnull, sizeof(HashTableEntry), 0);
if (!initialized) rv = NS_ERROR_OUT_OF_MEMORY;
return rv;
}
void
nsDiskCacheBindery::Reset()
{
if (initialized) {
PL_DHashTableFinish(&table);
initialized = false;
}
}
nsDiskCacheBinding *
nsDiskCacheBindery::CreateBinding(nsCacheEntry * entry,
nsDiskCacheRecord * record)
{
NS_ASSERTION(initialized, "nsDiskCacheBindery not initialized");
nsCOMPtr<nsISupports> data = entry->Data();
if (data) {
NS_ERROR("cache entry already has bind data");
return nsnull;
}
nsDiskCacheBinding * binding = new nsDiskCacheBinding(entry, record);
if (!binding) return nsnull;
// give ownership of the binding to the entry
entry->SetData(binding);
// add binding to collision detection system
nsresult rv = AddBinding(binding);
if (NS_FAILED(rv)) {
entry->SetData(nsnull);
return nsnull;
}
return binding;
}
/**
* FindActiveEntry : to find active colliding entry so we can doom it
*/
nsDiskCacheBinding *
nsDiskCacheBindery::FindActiveBinding(PRUint32 hashNumber)
{
NS_ASSERTION(initialized, "nsDiskCacheBindery not initialized");
// find hash entry for key
HashTableEntry * hashEntry;
hashEntry = (HashTableEntry *) PL_DHashTableOperate(&table, (void*) hashNumber, PL_DHASH_LOOKUP);
if (PL_DHASH_ENTRY_IS_FREE(hashEntry)) return nsnull;
// walk list looking for active entry
NS_ASSERTION(hashEntry->mBinding, "hash entry left with no binding");
nsDiskCacheBinding * binding = hashEntry->mBinding;
while (binding->mCacheEntry->IsDoomed()) {
binding = (nsDiskCacheBinding *)PR_NEXT_LINK(binding);
if (binding == hashEntry->mBinding) return nsnull;
}
return binding;
}
/**
* AddBinding
*
* Called from FindEntry() if we read an entry off of disk
* - it may already have a generation number
* - a generation number conflict is an error
*
* Called from BindEntry()
* - a generation number needs to be assigned
*/
nsresult
nsDiskCacheBindery::AddBinding(nsDiskCacheBinding * binding)
{
NS_ENSURE_ARG_POINTER(binding);
NS_ASSERTION(initialized, "nsDiskCacheBindery not initialized");
// find hash entry for key
HashTableEntry * hashEntry;
hashEntry = (HashTableEntry *) PL_DHashTableOperate(&table,
(void*) binding->mRecord.HashNumber(),
PL_DHASH_ADD);
if (!hashEntry) return NS_ERROR_OUT_OF_MEMORY;
if (hashEntry->mBinding == nsnull) {
hashEntry->mBinding = binding;
if (binding->mGeneration == 0)
binding->mGeneration = 1; // if generation uninitialized, set it to 1
return NS_OK;
}
// insert binding in generation order
nsDiskCacheBinding * p = hashEntry->mBinding;
bool calcGeneration = (binding->mGeneration == 0); // do we need to calculate generation?
if (calcGeneration) binding->mGeneration = 1; // initialize to 1 if uninitialized
while (1) {
if (binding->mGeneration < p->mGeneration) {
// here we are
PR_INSERT_BEFORE(binding, p);
if (hashEntry->mBinding == p)
hashEntry->mBinding = binding;
break;
}
if (binding->mGeneration == p->mGeneration) {
if (calcGeneration) ++binding->mGeneration; // try the next generation
else {
NS_ERROR("### disk cache: generations collide!");
return NS_ERROR_UNEXPECTED;
}
}
p = (nsDiskCacheBinding *)PR_NEXT_LINK(p);
if (p == hashEntry->mBinding) {
// end of line: insert here or die
p = (nsDiskCacheBinding *)PR_PREV_LINK(p); // back up and check generation
if (p->mGeneration == 255) {
NS_WARNING("### disk cache: generation capacity at full");
return NS_ERROR_UNEXPECTED;
}
PR_INSERT_BEFORE(binding, hashEntry->mBinding);
break;
}
}
return NS_OK;
}
/**
* RemoveBinding : remove binding from collision detection on deactivation
*/
void
nsDiskCacheBindery::RemoveBinding(nsDiskCacheBinding * binding)
{
NS_ASSERTION(initialized, "nsDiskCacheBindery not initialized");
if (!initialized) return;
HashTableEntry * hashEntry;
void * key = (void *)binding->mRecord.HashNumber();
hashEntry = (HashTableEntry*) PL_DHashTableOperate(&table,
(void*) key,
PL_DHASH_LOOKUP);
if (!PL_DHASH_ENTRY_IS_BUSY(hashEntry)) {
NS_WARNING("### disk cache: binding not in hashtable!");
return;
}
if (binding == hashEntry->mBinding) {
if (PR_CLIST_IS_EMPTY(binding)) {
// remove this hash entry
(void) PL_DHashTableOperate(&table,
(void*) binding->mRecord.HashNumber(),
PL_DHASH_REMOVE);
return;
} else {
// promote next binding to head, and unlink this binding
hashEntry->mBinding = (nsDiskCacheBinding *)PR_NEXT_LINK(binding);
}
}
PR_REMOVE_AND_INIT_LINK(binding);
}
/**
* ActiveBinding : PLDHashTable enumerate function to verify active bindings
*/
PLDHashOperator
ActiveBinding(PLDHashTable * table,
PLDHashEntryHdr * hdr,
PRUint32 number,
void * arg)
{
nsDiskCacheBinding * binding = ((HashTableEntry *)hdr)->mBinding;
NS_ASSERTION(binding, "### disk cache binding = nsnull!");
nsDiskCacheBinding * head = binding;
do {
if (binding->IsActive()) {
*((bool *)arg) = true;
return PL_DHASH_STOP;
}
binding = (nsDiskCacheBinding *)PR_NEXT_LINK(binding);
} while (binding != head);
return PL_DHASH_NEXT;
}
/**
* ActiveBindings : return true if any bindings have open descriptors
*/
bool
nsDiskCacheBindery::ActiveBindings()
{
NS_ASSERTION(initialized, "nsDiskCacheBindery not initialized");
if (!initialized) return false;
bool activeBinding = false;
PL_DHashTableEnumerate(&table, ActiveBinding, &activeBinding);
return activeBinding;
}