Myriad is actually fine, I double checked it for cross-platformed-ness. It

doesn't yet normalize the endian-ness, and I guess at this point to maintain
compatibility I'll have to make it a little endian format.  I would still like
to add better thread-safety to it, but that's about it.

1 files changed, 222 insertions, 0 deletions

diff --git a/src/stable/myriad.h b/src/stable/myriad.h
new file mode 100644
index 0000000..3382ab5
--- /dev/null
+++ b/src/stable/myriad.h
@@ -0,0 +1,222 @@
+/*
+ * Copyright (C) 2007-2011 Xagasoft, All rights reserved.
+ *
+ * This file is part of the libbu++ library and is released under the
+ * terms of the license contained in the file LICENSE.
+ */
+
+#ifndef BU_MYRIAD_H
+#define BU_MYRIAD_H
+
+#include <stdint.h>
+#include "bu/bitstring.h"
+#include "bu/exceptionbase.h"
+#include "bu/array.h"
+#include "bu/hash.h"
+
+namespace Bu
+{
+        class Stream;
+        class MyriadStream;
+
+        subExceptionDeclBegin( MyriadException )
+                enum
+                {
+                        emptyStream,
+                        invalidFormat,
+                        badVersion,
+                        invalidWordSize,
+                        noSuchStream,
+                        streamExists,
+                        invalidStreamId,
+                        protectedStream
+                };
+        subExceptionDeclEnd();
+
+        /**
+         * Myriad block-allocated stream multiplexing system.  This is a system for
+         * creating streams that contain other streams in a flexible and lightweight
+         * manner.  Basically, you can create a file (or any other stream) that can
+         * store any number of flexible, growing streams.  The streams within the
+         * Myriad stream are automatically numbered, not named.  This works more
+         * or less like a filesystem, but without the extra layer for managing
+         * file and directory links.  This would actually be very easy to add
+         * on top of Myriad, but is not required.
+         *
+         * Header format is as follows:
+         *
+         * MMMMvBssssSSSS*
+         * M = Magic number (0AD3FA84)
+         * v = version number
+         * B = Bits per int
+         * s = Blocksize in bytes
+         * S = Number of Streams
+         * 
+         * The * represents the Stream headers, one per stream, as follows:
+         * IIIIssss$
+         * I = Id number of the stream
+         * s = size of stream in bytes
+         *
+         * The $ represents the Block headers, one per used block, as  follows:
+         * IIII
+         * I = Index of the block
+         *
+         * The stream/block data is interleaved in the header, so all blocks stored
+         * with one stream are together.  The block headers are in order, and the
+         * data in them is required to be "solid" you cannot fill partial blocks
+         * mid-way through a stream.
+         *
+         * The initial block starts with the nids header, and is both the zero block
+         * and the zero stream.  For now, the minimum block size is the size needed
+         * to store the base header, the zero stream header, and the first two
+         * blocks of the zero stream, so 30 bytes.  Since it's reccomended to use
+         * a size that will fit evenly into filesystem blocks, then a size of 32 is
+         * probably the smallest reccomended size because all powers of two equal
+         * to or greater than 32 are evenly divisible by 32.
+         *
+         * I have had a thought that if the block size were smaller than 42 bytes
+         * the header would consume the first N blocks where N * block size is
+         * enough space to house the initial header, the first stream header, and
+         * the first N block headers.  This, of course, causes you to hit an
+         * infinite header if the block size is small enough.
+         */
+        class Myriad
+        {
+                friend class MyriadStream;
+        public:
+                /**
+                 * Create a Myriad object that uses the given stream to store data.
+                 * This stream must be random access.  The block size and preallocate
+                 * values passed in are values that will be used if the given stream
+                 * is empty.  In that case the stream will be "formatted" for myriad
+                 * with the specified block size.  If there is already a viable Myriad
+                 * format present in the stream, then the blocksize and preallocate
+                 * values will be ignored and the values from the stream will be used
+                 * instead.  If the stream doesn't appear to be Myriad formatted an
+                 * exception will be thrown.
+                 */
+                Myriad( Bu::Stream &sStore, int iBlockSize=512, int iPreallocate=8 );
+                virtual ~Myriad();
+
+                /**
+                 * Destroy whatever data may be in the base stream and create a new
+                 * Myriad system there with the given blocksize.  Use this with care,
+                 * it will destroy anything that was already in the stream, and
+                 * generally, should not ever have to be used.
+                 */
+                void initialize( int iBlockSize, int iPreAllocate=1 );
+
+                /**
+                 * Create a new stream within the Myriad system.  The ID of the new
+                 * stream is returned.
+                 */
+                int createStream( int iPreAllocate=1 );
+
+                /**
+                 * Create a new stream within the Myriad system with a given id.  The
+                 * id that you provide will be the new id of the stream unless it's
+                 * already used, in which case an error is thrown.  This is primarilly
+                 * useful when copying an old Myriad file into a new one.
+                 */
+                int createStreamWithId( int iId, int iPreAllocate=1 );
+
+                /**
+                 * Delete a stream that's already within the Myriad.
+                 */
+                void deleteStream( int iId );
+
+                /**
+                 * Return a new Stream object assosiated with the given stream ID.
+                 */
+                MyriadStream openStream( int iId );
+
+                Bu::Array<int> getStreamIds();
+                int getStreamSize( int iId );
+                bool hasStream( int iId );
+
+                int getNumStreams();
+                int getBlockSize();
+                int getNumBlocks();
+                int getNumUsedBlocks();
+                int getTotalUsedBytes();
+                int getTotalUnusedBytes();
+                int getTotalUnusedBytes( int iFakeBlockSize );
+
+                /**
+                 * Syncronize the header data, etc. with the storage stream.  It's not
+                 * a bad idea to call this periodically.
+                 */
+                void sync();
+
+                /**
+                 * Read the first few bytes from the given stream and return true/false
+                 * depending on weather or not it's a Myriad stream.  This will throw
+                 * an exception if the stream is empty, or is not random access.
+                 */
+                static bool isMyriad( Bu::Stream &sStore );
+
+                const Bu::BitString &getBlocksUsed() const;
+
+        private:
+                /**
+                 * Initialize this object based on the data already in the assosiated
+                 * stream.  This will be called automatically for you if you forget,
+                 * but if you want to pre-initialize for some reason, just call this
+                 * once before you actually start doing anything with your Myriad.
+                 */
+                void initialize();
+
+                enum
+                {
+                        blockUnused     =       0xFFFFFFFFUL
+                };
+                
+                typedef Bu::Array<int> BlockArray;
+                class Stream
+                {
+                public:
+                        int iId;
+                        int iSize;
+                        BlockArray aBlocks;
+                };
+                typedef Bu::Array<Stream *> StreamArray;
+
+                class Block
+                {
+                public:
+                        char *pData;
+                        bool bChanged;
+                        int iBlockIndex;
+                };
+
+                void updateHeader();
+                int findEmptyBlock();
+
+                /**
+                 *@todo Change this to use a binary search, it's nicer.
+                 */
+                Stream *findStream( int iId );
+
+                Block *getBlock( int iBlock );
+                void releaseBlock( Block *pBlock );
+                void syncBlock( Block *pBlock );
+
+                int streamAddBlock( Stream *pStream );
+                void setStreamSize( Stream *pStream, long iSize );
+
+                void headerChanged();
+
+        private:
+                Bu::Stream &sStore;
+                int iBlockSize;
+                int iBlocks;
+                int iUsed;
+                Bu::BitString bsBlockUsed;
+                StreamArray aStreams;
+                typedef Bu::Hash<int, Block *> BlockHash;
+                BlockHash hActiveBlocks;
+                bool bHeaderChanged;
+        };
+};
+
+#endif