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pjs/xpcom/io/nsFastLoadFile.h

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/* -*- 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 Mozilla FastLoad code.
*
* 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):
* Brendan Eich <brendan@mozilla.org> (original author)
*
* Alternatively, the contents of this file may be used under the terms of
* either of 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 ***** */
#ifndef nsFastLoadFile_h___
#define nsFastLoadFile_h___
/**
* Mozilla FastLoad file format and helper types.
*/
#include "prtypes.h"
#include "pldhash.h"
#include "nsBinaryStream.h"
#include "nsCOMPtr.h"
#include "nsDebug.h"
#include "nsID.h"
#include "nsMemory.h"
#include "nsVoidArray.h"
#include "nsIFastLoadFileControl.h"
#include "nsIFastLoadService.h"
#include "nsISeekableStream.h"
#include "nsISupportsArray.h"
/**
* FastLoad file Object ID (OID) is an identifier for multiply and cyclicly
* connected objects in the serialized graph of all reachable objects.
*
* Holy Mixed Metaphors: JS, after Common Lisp, uses #n= to define a "sharp
* variable" naming an object that's multiply or cyclicly connected, and #n#
* to stand for a connection to an already-defined object. We too call any
* object with multiple references "sharp", and (here it comes) any object
* with only one reference "dull".
*
* Note that only sharp objects require a mapping from OID to FastLoad file
* offset and other information. Dull objects can be serialized _in situ_
* (where they are referenced) and deserialized when their (singular, shared)
* OID is scanned.
*
* We also compress 16-byte XPCOM IDs into 32-bit dense identifiers to save
* space. See nsFastLoadFooter, below, for the mapping data structure used to
* compute an nsID given an NSFastLoadID.
*/
typedef PRUint32 NSFastLoadID; // nsFastLoadFooter::mIDMap index
typedef PRUint32 NSFastLoadOID; // nsFastLoadFooter::mObjectMap index
/**
* A Mozilla FastLoad file is an untagged (in general) stream of objects and
* primitive-type data. Small integers are fairly common, and could easily be
* confused for NSFastLoadIDs and NSFastLoadOIDs. To help catch bugs where
* reader and writer code fail to match, we XOR unlikely 32-bit numbers with
* NSFastLoad*IDs when storing and fetching. The following unlikely values are
* irrational numbers ((sqrt(5)-1)/2, sqrt(2)-1) represented in fixed point.
*
* The reader XORs, converts the ID to an index, and bounds-checks all array
* accesses that use the index. Array access code asserts that the index is in
* bounds, and returns a dummy array element if it isn't.
*/
#define MFL_ID_XOR_KEY 0x9E3779B9 // key XOR'd with ID when serialized
#define MFL_OID_XOR_KEY 0x6A09E667 // key XOR'd with OID when serialized
/**
* An OID can be tagged to introduce the serialized definition of the object,
* or to stand for a strong or weak reference to that object. Thus the high
* 29 bits actually identify the object, and the low three bits tell whether
* the object is being defined or just referenced -- and via what inheritance
* chain or inner object, if necessary.
*
* The MFL_QUERY_INTERFACE_TAG bit helps us cope with aggregation and multiple
* inheritance: object identity follows the XPCOM rule, but a deserializer may
* need to query for an interface not on the primary inheritance chain ending
* in the nsISupports whose address uniquely identifies the XPCOM object being
* referenced or defined.
*/
#define MFL_OBJECT_TAG_BITS 3
#define MFL_OBJECT_TAG_MASK PR_BITMASK(MFL_OBJECT_TAG_BITS)
#define MFL_OBJECT_DEF_TAG 1U // object definition follows this OID
#define MFL_WEAK_REF_TAG 2U // OID weakly refers to a prior object
// NB: do not confuse with nsWeakPtr!
#define MFL_QUERY_INTERFACE_TAG 4U // QI object to the ID follows this OID
// NB: an NSFastLoadID, not an nsIID!
/**
* The dull object identifier introduces the definition of all objects that
* have only one (necessarily strong) ref in the serialization. The definition
* appears at the point of reference.
*/
#define MFL_DULL_OBJECT_OID MFL_OBJECT_DEF_TAG
/**
* Convert an OID to an index into nsFastLoadFooter::mObjectMap.
*/
#define MFL_OID_TO_SHARP_INDEX(oid) (((oid) >> MFL_OBJECT_TAG_BITS) - 1)
#define MFL_SHARP_INDEX_TO_OID(index) (((index) + 1) << MFL_OBJECT_TAG_BITS)
/**
* Magic "number" at start of a FastLoad file. Inspired by the PNG "magic"
* string, which inspired XPCOM's typelib (.xpt) file magic. Guaranteed to be
* corrupted by FTP-as-ASCII and other likely errors, meaningful to clued-in
* humans, and ending in ^Z to terminate erroneous text input on Windows.
*/
#define MFL_FILE_MAGIC "XPCOM\nMozFASL\r\n\032"
#define MFL_FILE_MAGIC_SIZE 16
#define MFL_FILE_VERSION_0 0
#define MFL_FILE_VERSION_1 1000
#define MFL_FILE_VERSION 4 // fix to note singletons in object map
/**
* Compute Fletcher's 16-bit checksum over aLength bytes starting at aBuffer,
* with the initial accumulators seeded from *aChecksum, and final checksum
* returned in *aChecksum. The return value is the number of unchecked bytes,
* which may be non-zero if aBuffer is misaligned or aLength is odd. Callers
* should copy any remaining bytes to the front of the next buffer.
*
* If aLastBuffer is false, do not check any bytes remaining due to misaligned
* aBuffer or odd aLength, instead returning the remaining byte count. But if
* aLastBuffer is true, treat aBuffer as the last buffer in the file and check
* every byte, returning 0. Here's a read-loop checksumming sketch:
*
* char buf[BUFSIZE];
* PRUint32 len, rem = 0;
* PRUint32 checksum = 0;
*
* while (NS_SUCCEEDED(rv = Read(buf + rem, sizeof buf - rem, &len)) && len) {
* len += rem;
* rem = NS_AccumulateFastLoadChecksum(&checksum,
* NS_REINTERPRET_CAST(PRUint8*, buf),
* len,
* PR_FALSE);
* if (rem)
* memcpy(buf, buf + len - rem, rem);
* }
*
* if (rem) {
* NS_AccumulateFastLoadChecksum(&checksum,
* NS_REINTERPRET_CAST(PRUint8*, buf),
* rem,
* PR_TRUE);
* }
*
* After this, if NS_SUCCEEDED(rv), checksum contains a valid FastLoad sum.
*/
PR_EXTERN(PRUint32)
NS_AccumulateFastLoadChecksum(PRUint32 *aChecksum,
const PRUint8* aBuffer,
PRUint32 aLength,
PRBool aLastBuffer);
PR_EXTERN(PRUint32)
NS_AddFastLoadChecksums(PRUint32 sum1, PRUint32 sum2, PRUint32 sum2ByteCount);
/**
* Header at the start of a FastLoad file.
*/
struct nsFastLoadHeader {
char mMagic[MFL_FILE_MAGIC_SIZE];
PRUint32 mChecksum;
PRUint32 mVersion;
PRUint32 mFooterOffset;
PRUint32 mFileSize;
};
/**
* Footer prefix structure (footer header, ugh), after which come arrays of
* structures or strings counted by these members.
*/
struct nsFastLoadFooterPrefix {
PRUint32 mNumIDs;
PRUint32 mNumSharpObjects;
PRUint32 mNumMuxedDocuments;
PRUint32 mNumDependencies;
};
struct nsFastLoadSharpObjectInfo {
PRUint32 mCIDOffset; // offset of object's NSFastLoadID and data
PRUint16 mStrongRefCnt;
PRUint16 mWeakRefCnt; // high bit is singleton flag, see below
};
#define MFL_SINGLETON_FLAG 0x8000
#define MFL_WEAK_REFCNT_MASK 0x7fff
#define MFL_GET_SINGLETON_FLAG(ip) ((ip)->mWeakRefCnt & MFL_SINGLETON_FLAG)
#define MFL_GET_WEAK_REFCNT(ip) ((ip)->mWeakRefCnt & MFL_WEAK_REFCNT_MASK)
#define MFL_SET_SINGLETON_FLAG(ip) \
((ip)->mWeakRefCnt |= MFL_SINGLETON_FLAG)
#define MFL_SET_WEAK_REFCNT(ip,rc) \
((ip)->mWeakRefCnt = (((ip)->mWeakRefCnt & MFL_SINGLETON_FLAG) | (rc)))
#define MFL_BUMP_WEAK_REFCNT(ip) (++(ip)->mWeakRefCnt)
#define MFL_DROP_WEAK_REFCNT(ip) (--(ip)->mWeakRefCnt)
struct nsFastLoadMuxedDocumentInfo {
const char* mURISpec;
PRUint32 mInitialSegmentOffset;
};
// forward declarations of opaque types defined in nsFastLoadFile.cpp
struct nsDocumentMapReadEntry;
struct nsDocumentMapWriteEntry;
// So nsFastLoadFileUpdater can verify that its nsIObjectInputStream parameter
// is an nsFastLoadFileReader.
#define NS_FASTLOADFILEREADER_IID \
{0x7d37d1bb,0xcef3,0x4c5f,{0x97,0x68,0x0f,0x89,0x7f,0x1a,0xe1,0x40}}
struct nsIFastLoadFileReader : public nsISupports {
NS_DEFINE_STATIC_IID_ACCESSOR(NS_FASTLOADFILEREADER_IID)
};
/**
* Inherit from the concrete class nsBinaryInputStream, which inherits from
* abstract nsIObjectInputStream but does not implement its direct methods.
* Though the names are not as clear as I'd like, this seems to be the best
* way to share nsBinaryStream.cpp code.
*/
class nsFastLoadFileReader
: public nsBinaryInputStream,
public nsIFastLoadReadControl,
public nsISeekableStream,
public nsIFastLoadFileReader
{
public:
nsFastLoadFileReader(nsIInputStream *aStream)
: mCurrentDocumentMapEntry(nsnull) {
SetInputStream(aStream);
MOZ_COUNT_CTOR(nsFastLoadFileReader);
}
virtual ~nsFastLoadFileReader() {
MOZ_COUNT_DTOR(nsFastLoadFileReader);
}
private:
// nsISupports methods
NS_DECL_ISUPPORTS_INHERITED
// overridden nsIObjectInputStream methods
NS_IMETHOD ReadObject(PRBool aIsStrongRef, nsISupports* *_retval);
NS_IMETHOD ReadID(nsID *aResult);
// nsIFastLoadFileControl methods
NS_DECL_NSIFASTLOADFILECONTROL
// nsIFastLoadReadControl methods
NS_DECL_NSIFASTLOADREADCONTROL
// nsISeekableStream methods
NS_DECL_NSISEEKABLESTREAM
// Override Read so we can demultiplex a document interleaved with others.
NS_IMETHOD Read(char* aBuffer, PRUint32 aCount, PRUint32 *aBytesRead);
// Override ReadSegments too, as nsBinaryInputStream::ReadSegments does
// not call through our overridden Read method -- it calls directly into
// the underlying input stream.
NS_IMETHODIMP ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
PRUint32 aCount, PRUint32 *aResult);
nsresult ReadHeader(nsFastLoadHeader *aHeader);
/**
* In-memory representation of an indexed nsFastLoadSharpObjectInfo record.
*/
struct nsObjectMapEntry : public nsFastLoadSharpObjectInfo {
nsCOMPtr<nsISupports> mReadObject;
PRInt64 mSkipOffset;
PRUint16 mSaveStrongRefCnt; // saved for an Update
PRUint16 mSaveWeakRefCnt; // after a Read
};
/**
* In-memory representation of the FastLoad file footer.
*/
struct nsFastLoadFooter : public nsFastLoadFooterPrefix {
nsFastLoadFooter()
: mIDMap(nsnull),
mObjectMap(nsnull) {
mDocumentMap.ops = mURIMap.ops = nsnull;
}
~nsFastLoadFooter() {
delete[] mIDMap;
delete[] mObjectMap;
if (mDocumentMap.ops)
PL_DHashTableFinish(&mDocumentMap);
if (mURIMap.ops)
PL_DHashTableFinish(&mURIMap);
}
// These can't be static within GetID and GetSharpObjectEntry or the
// toolchains on HP-UX 10.20's, RH 7.0, and Mac OS X all barf at link
// time ("common symbols not allowed with MY_DHLIB output format", to
// quote the OS X rev of gcc).
static nsID gDummyID;
static nsObjectMapEntry gDummySharpObjectEntry;
const nsID& GetID(NSFastLoadID aFastId) const {
PRUint32 index = aFastId - 1;
NS_ASSERTION(index < mNumIDs, "aFastId out of range");
if (index >= mNumIDs)
return gDummyID;
return mIDMap[index];
}
nsObjectMapEntry&
GetSharpObjectEntry(NSFastLoadOID aOID) const {
PRUint32 index = MFL_OID_TO_SHARP_INDEX(aOID);
NS_ASSERTION(index < mNumSharpObjects, "aOID out of range");
if (index >= mNumSharpObjects)
return gDummySharpObjectEntry;
return mObjectMap[index];
}
// Map from dense, zero-based, uint32 NSFastLoadID to 16-byte nsID.
nsID* mIDMap;
// Map from dense, zero-based MFL_OID_TO_SHARP_INDEX(oid) to sharp
// object offset and refcnt information.
nsObjectMapEntry* mObjectMap;
// Map from URI spec string to nsDocumentMapReadEntry, which helps us
// demultiplex a document's objects from among the interleaved object
// stream segments in the FastLoad file.
PLDHashTable mDocumentMap;
// Fast mapping from URI object pointer to mDocumentMap entry, valid
// only while the muxed document is loading.
PLDHashTable mURIMap;
// List of source filename dependencies that should trigger regeneration
// of the FastLoad file.
nsCOMPtr<nsISupportsArray> mDependencies;
};
nsresult ReadFooter(nsFastLoadFooter *aFooter);
nsresult ReadFooterPrefix(nsFastLoadFooterPrefix *aFooterPrefix);
nsresult ReadSlowID(nsID *aID);
nsresult ReadFastID(NSFastLoadID *aID);
nsresult ReadSharpObjectInfo(nsFastLoadSharpObjectInfo *aInfo);
nsresult ReadMuxedDocumentInfo(nsFastLoadMuxedDocumentInfo *aInfo);
nsresult DeserializeObject(nsISupports* *aObject);
nsresult Open();
NS_IMETHOD Close();
protected:
nsFastLoadHeader mHeader;
nsFastLoadFooter mFooter;
nsDocumentMapReadEntry* mCurrentDocumentMapEntry;
friend class nsFastLoadFileUpdater;
};
NS_COM nsresult
NS_NewFastLoadFileReader(nsIObjectInputStream* *aResult,
nsIInputStream* aSrcStream);
/**
* Inherit from the concrete class nsBinaryInputStream, which inherits from
* abstract nsIObjectInputStream but does not implement its direct methods.
* Though the names are not as clear as I'd like, this seems to be the best
* way to share nsBinaryStream.cpp code.
*/
class nsFastLoadFileWriter
: public nsBinaryOutputStream,
public nsIFastLoadWriteControl,
public nsISeekableStream
{
public:
nsFastLoadFileWriter(nsIOutputStream *aStream, nsIFastLoadFileIO* aFileIO)
: mCurrentDocumentMapEntry(nsnull),
mFileIO(aFileIO)
{
SetOutputStream(aStream);
mHeader.mChecksum = 0;
mIDMap.ops = mObjectMap.ops = mDocumentMap.ops = mURIMap.ops = nsnull;
mDependencyMap.ops = nsnull;
MOZ_COUNT_CTOR(nsFastLoadFileWriter);
}
virtual ~nsFastLoadFileWriter()
{
if (mIDMap.ops)
PL_DHashTableFinish(&mIDMap);
if (mObjectMap.ops)
PL_DHashTableFinish(&mObjectMap);
if (mDocumentMap.ops)
PL_DHashTableFinish(&mDocumentMap);
if (mURIMap.ops)
PL_DHashTableFinish(&mURIMap);
if (mDependencyMap.ops)
PL_DHashTableFinish(&mDependencyMap);
MOZ_COUNT_DTOR(nsFastLoadFileWriter);
}
private:
// nsISupports methods
NS_DECL_ISUPPORTS_INHERITED
// overridden nsIObjectOutputStream methods
NS_IMETHOD WriteObject(nsISupports* aObject, PRBool aIsStrongRef);
NS_IMETHOD WriteSingleRefObject(nsISupports* aObject);
NS_IMETHOD WriteCompoundObject(nsISupports* aObject,
const nsIID& aIID,
PRBool aIsStrongRef);
NS_IMETHOD WriteID(const nsID& aID);
// nsIFastLoadFileControl methods
NS_DECL_NSIFASTLOADFILECONTROL
// nsIFastLoadWriteControl methods
NS_DECL_NSIFASTLOADWRITECONTROL
// nsISeekableStream methods
NS_DECL_NSISEEKABLESTREAM
nsresult MapID(const nsID& aSlowID, NSFastLoadID *aResult);
nsresult WriteHeader(nsFastLoadHeader *aHeader);
nsresult WriteFooter();
nsresult WriteFooterPrefix(const nsFastLoadFooterPrefix& aFooterPrefix);
nsresult WriteSlowID(const nsID& aID);
nsresult WriteFastID(NSFastLoadID aID);
nsresult WriteSharpObjectInfo(const nsFastLoadSharpObjectInfo& aInfo);
nsresult WriteMuxedDocumentInfo(const nsFastLoadMuxedDocumentInfo& aInfo);
nsresult Init();
nsresult Open();
NS_IMETHOD Close();
nsresult WriteObjectCommon(nsISupports* aObject,
PRBool aIsStrongRef,
PRUint32 aQITag);
static PLDHashOperator PR_CALLBACK
IDMapEnumerate(PLDHashTable *aTable,
PLDHashEntryHdr *aHdr,
PRUint32 aNumber,
void *aData);
static PLDHashOperator PR_CALLBACK
ObjectMapEnumerate(PLDHashTable *aTable,
PLDHashEntryHdr *aHdr,
PRUint32 aNumber,
void *aData);
static PLDHashOperator PR_CALLBACK
DocumentMapEnumerate(PLDHashTable *aTable,
PLDHashEntryHdr *aHdr,
PRUint32 aNumber,
void *aData);
static PLDHashOperator PR_CALLBACK
DependencyMapEnumerate(PLDHashTable *aTable,
PLDHashEntryHdr *aHdr,
PRUint32 aNumber,
void *aData);
protected:
nsFastLoadHeader mHeader;
PLDHashTable mIDMap;
PLDHashTable mObjectMap;
PLDHashTable mDocumentMap;
PLDHashTable mURIMap;
PLDHashTable mDependencyMap;
nsDocumentMapWriteEntry* mCurrentDocumentMapEntry;
nsCOMPtr<nsIFastLoadFileIO> mFileIO;
};
NS_COM nsresult
NS_NewFastLoadFileWriter(nsIObjectOutputStream* *aResult,
nsIOutputStream* aDestStream,
nsIFastLoadFileIO* aFileIO);
/**
* Subclass of nsFastLoadFileWriter, friend of nsFastLoadFileReader which it
* wraps when a FastLoad file needs to be updated. The wrapped reader can be
* used to demulitplex data for documents already in the FastLoad file, while
* the updater writes new data over the old footer, then writes a new footer
* that maps all data on Close.
*/
class nsFastLoadFileUpdater
: public nsFastLoadFileWriter,
nsIFastLoadFileIO
{
public:
nsFastLoadFileUpdater(nsIOutputStream* aOutputStream)
: nsFastLoadFileWriter(aOutputStream, nsnull) {
MOZ_COUNT_CTOR(nsFastLoadFileUpdater);
}
virtual ~nsFastLoadFileUpdater() {
MOZ_COUNT_DTOR(nsFastLoadFileUpdater);
}
private:
// nsISupports methods
NS_DECL_ISUPPORTS_INHERITED
// nsIFastLoadFileIO methods
NS_DECL_NSIFASTLOADFILEIO
nsresult Open(nsFastLoadFileReader* aReader);
NS_IMETHOD Close();
static PLDHashOperator PR_CALLBACK
CopyReadDocumentMapEntryToUpdater(PLDHashTable *aTable,
PLDHashEntryHdr *aHdr,
PRUint32 aNumber,
void *aData);
friend class nsFastLoadFileReader;
protected:
nsCOMPtr<nsIInputStream> mInputStream;
};
NS_COM nsresult
NS_NewFastLoadFileUpdater(nsIObjectOutputStream* *aResult,
nsIOutputStream* aOutputStream,
nsIObjectInputStream* aReaderAsStream);
#endif // nsFastLoadFile_h___
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