bufcache.h File Reference

#include <sys/queue.h>

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Data Structures
struct	BufCacheEntry

Typedefs
typedef struct BufCacheEntry	BufCacheEntry

Functions
void	BufCache_Init ()
int	BufCache_Alloc (Disk *disk, uint64_t diskOffset, BufCacheEntry **entry)
void	BufCache_Release (BufCacheEntry *entry)
int	BufCache_Read (Disk *disk, uint64_t diskOffset, BufCacheEntry **entry)
int	BufCache_Write (BufCacheEntry *entry)

Typedef Documentation

BufCacheEntry

typedef struct BufCacheEntry BufCacheEntry

Function Documentation

BufCache_Alloc()

int BufCache_Alloc	(	Disk *	disk,
		uint64_t	diskOffset,
		BufCacheEntry **	entry
	)

BufCache_Alloc –

Allocate a buffer cache entry to allow writing new data to disk.

Parameters

[in]	disk	Disk object
[in]	diskOffset	Block offset within the disk
[out]	entry	If successful, this contains the buffer cache entry.

Return values

0	if successful

Returns

Otherwise returns an error code.

Definition at line 178 of file bufcache.c.

{
    int status;
 
    Spinlock_Lock(&cacheLock);
 
    status = BufCacheLookup(disk, diskOffset, entry);
    if (*entry == NULL) {
        status = BufCacheAlloc(disk, diskOffset, entry);
    }
 
    cacheAlloc++;
 
    Spinlock_Unlock(&cacheLock);
 
    return status;
}

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BufCache_Init()

void BufCache_Init

(

)

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BufCache_Read()

int BufCache_Read	(	Disk *	disk,
		uint64_t	diskOffset,
		BufCacheEntry **	entry
	)

BufCache_Read –

Read block from disk into the buffer cache.

Parameters

[in]	disk	Disk object
[in]	diskOffset	Block offset within the disk
[out]	entry	If successful, this contains the buffer cache entry.

Return values

0	if successful

Returns

Otherwise returns an error code.

Definition at line 229 of file bufcache.c.

{
    int status;
    void *buf;
    SGArray sga;
 
    Spinlock_Lock(&cacheLock);
    status = BufCacheLookup(disk, diskOffset, entry);
    if (*entry != NULL) {
        cacheHit++;
        Spinlock_Unlock(&cacheLock);
        return status;
    }
    cacheMiss++;
 
    status = BufCacheAlloc(disk, diskOffset, entry);
    if (status != 0) {
        Spinlock_Unlock(&cacheLock);
        return status;
    }
 
    buf = (*entry)->buffer;
    SGArray_Init(&sga);
    SGArray_Append(&sga, diskOffset, BLOCKSIZE);
 
    /*
     * XXX: Need to avoid holding cacheLock while reading from the disk, but 
     * need ensure other cores doesn't issue a read to the same block.
     */
    status = Disk_Read(disk, buf, &sga, NULL, NULL);
    Spinlock_Unlock(&cacheLock);
 
    return status;
}

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BufCache_Release()

void BufCache_Release

(

BufCacheEntry *

entry

)

BufCache_Release –

Release a buffer cache entry. If no other references are held the buffer cache entry is placed on the LRU list.

Parameters

[in]

entry

Buffer cache entry.

Definition at line 205 of file bufcache.c.

{
    Spinlock_Lock(&cacheLock);
 
    entry->refCount--;
    if (entry->refCount == 0) {
        TAILQ_INSERT_TAIL(&lruList, entry, lruEntry);
    }
 
    Spinlock_Unlock(&cacheLock);
}

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BufCache_Write()

int BufCache_Write

(

BufCacheEntry *

entry

)

BufCache_Write –

Write a buffer cache entry to disk.

Return values

0	if successful

Returns

Otherwise an error code is returned.

Definition at line 273 of file bufcache.c.

{
    void *buf = entry->buffer;
    SGArray sga;
 
    SGArray_Init(&sga);
    SGArray_Append(&sga, entry->diskOffset, BLOCKSIZE);
 
    return Disk_Write(entry->disk, buf, &sga, NULL, NULL);
}

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