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- typedef struct Source Source;
- typedef struct VacFile VacFile;
- typedef struct MetaBlock MetaBlock;
- typedef struct MetaEntry MetaEntry;
- typedef struct Lump Lump;
- typedef struct Cache Cache;
- #pragma incomplete Cache
- enum {
- NilBlock = (~0UL),
- MaxBlock = (1UL<<31),
- };
- struct VacFS {
- int ref;
-
- /* need a read write lock? */
- uchar score[VtScoreSize];
- VacFile *root;
-
- VtSession *z;
- int readOnly;
- int bsize; /* maximum block size */
- uvlong qid; /* next qid */
- Cache *cache;
- };
- struct Source {
- VtLock *lk;
- Cache *cache; /* immutable */
- int readOnly; /* immutable */
- VacFile *vf; /* pointer back */
- Lump *lump; /* lump containing venti dir entry */
- ulong block; /* block number within parent: immutable */
- int entry; /* which entry in the block: immutable */
- /* most of a VtEntry, except the score */
- ulong gen; /* generation: immutable */
- int dir; /* dir flags: immutable */
- int depth; /* number of levels of pointer blocks */
- int psize; /* pointer block size: immutable */
- int dsize; /* data block size: immutable */
- uvlong size; /* size in bytes of file */
- int epb; /* dir entries per block = dize/VtEntrySize: immutable */
- };
- struct MetaEntry {
- uchar *p;
- ushort size;
- };
- struct MetaBlock {
- int maxsize; /* size of block */
- int size; /* size used */
- int free; /* free space within used size */
- int maxindex; /* entries allocated for table */
- int nindex; /* amount of table used */
- int unbotch;
- uchar *buf;
- };
- /*
- * contains a one block buffer
- * to avoid problems of the block changing underfoot
- * and to enable an interface that supports unget.
- */
- struct VacDirEnum {
- VacFile *file;
-
- ulong block; /* current block */
- MetaBlock mb; /* parsed version of block */
- int index; /* index in block */
- };
- /* Lump states */
- enum {
- LumpFree,
- LumpVenti, /* on venti server: score > 2^32: just a cached copy */
- LumpActive, /* active */
- LumpActiveRO, /* active: read only block */
- LumpActiveA, /* active: achrived */
- LumpSnap, /* snapshot: */
- LumpSnapRO, /* snapshot: read only */
- LumpSnapA, /* snapshot: achived */
- LumpZombie, /* block with no pointer to it: waiting to be freed */
-
- LumpMax
- };
- /*
- * Each lump has a state and generation
- * The following invariants are maintained
- * Each lump has no more than than one parent per generation
- * For Active*, no child has a parent of a greater generation
- * For Snap*, there is a snap parent of given generation and there are
- * no parents of greater gen - implies no children of a greater gen
- * For *RO, the lump is fixed - no change can be made - all pointers
- * are valid venti addresses
- * For *A, the lump is on the venti server
- * There are no pointers to Zombie lumps
- *
- * Transitions
- * Archiver at generation g
- * Mutator at generation h
- *
- * Want to modify a lump
- * Venti: create new Active(h)
- * Active(x): x == h: do nothing
- * Acitve(x): x < h: change to Snap(h-1) + add Active(h)
- * ActiveRO(x): change to SnapRO(h-1) + add Active(h)
- * ActiveA(x): add Active(h)
- * Snap*(x): should not occur
- * Zombie(x): should not occur
- * Want to archive
- * Active(x): x != g: should never happen
- * Active(x): x == g fix children and free them: move to ActoveRO(g);
- * ActiveRO(x): x != g: should never happen
- * ActiveRO(x): x == g: wait until it hits ActiveA or SnapA
- * ActiveA(x): done
- * Active(x): x < g: should never happen
- * Snap(x): x >= g: fix children, freeing all SnapA(y) x == y;
- * SnapRO(x): wait until it hits SnapA
- *
- */
- struct Lump {
- int ref;
- Cache *c;
- VtLock *lk;
-
- int state;
- ulong gen;
- uchar *data;
- uchar score[VtScoreSize]; /* score of packet */
- uchar vscore[VtScoreSize]; /* venti score - when archived */
- u8int type; /* type of packet */
- int dir; /* part of a directory - extension of type */
- u16int asize; /* allocated size of block */
- Lump *next; /* doubly linked hash chains */
- Lump *prev;
- u32int heap; /* index in heap table */
- u32int used; /* last reference times */
- u32int used2;
- u32int addr; /* mutable block address */
- };
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