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wrote Seg_exist, Seg_set, refined CacheSystem_init

This commit is contained in:
Fufu Fang 2019-04-21 20:48:44 +01:00
parent b1971a7c3f
commit 0c55dc5a0c
2 changed files with 243 additions and 174 deletions
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323
src/cache.c
View File

@ -2,6 +2,7 @@
#include "util.h"
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
@ -42,148 +43,76 @@ char *META_DIR;
*/
char *DATA_DIR;
void Cache_init(const char *dir)
void CacheSystem_init(const char *path)
{
META_DIR = strndupcat(dir, "meta/", MAX_PATH_LEN);
DATA_DIR = strndupcat(dir, "data/", MAX_PATH_LEN);
}
DIR* dir;
Cache *Cache_alloc()
{
Cache *cf = calloc(1, sizeof(Cache));
if (!cf) {
fprintf(stderr, "Cache_new(): calloc failure!\n");
/*
* Check if the top-level cache directory exists, if not, exit the
* program. We don't want to unintentionally create a folder
*/
dir = opendir(path);
if (dir) {
closedir(dir);
} else {
fprintf(stderr,
"CacheSystem_init(): opendir(): %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
return cf;
}
void Cache_free(Cache *cf)
{
if (cf->filename) {
free(cf->filename);
}
if (cf->seg) {
free(cf->seg);
}
free(cf);
}
int Cache_exist(const char *fn)
{
int meta_exists = 1;
int data_exists = 1;
char *metafn = strndupcat(META_DIR, fn, MAX_PATH_LEN);
char *datafn = strndupcat(DATA_DIR, fn, MAX_PATH_LEN);
if (access(metafn, F_OK)) {
fprintf(stderr, "Cache_exist(): access(): %s\n", strerror(errno));
meta_exists = 0;
/* Handle the case of missing '/' */
if (path[strnlen(path, MAX_PATH_LEN) - 1] == '/') {
META_DIR = strndupcat(path, "meta/", MAX_PATH_LEN);
DATA_DIR = strndupcat(path, "data/", MAX_PATH_LEN);
} else {
META_DIR = strndupcat(path, "/meta/", MAX_PATH_LEN);
DATA_DIR = strndupcat(path, "/data/", MAX_PATH_LEN);
}
if (access(datafn, F_OK)) {
fprintf(stderr, "Cache_exist(): access(): %s\n", strerror(errno));
data_exists = 0;
}
if (meta_exists ^ data_exists) {
if (meta_exists) {
if(unlink(metafn)) {
fprintf(stderr, "Cache_exist(): unlink(): %s\n",
strerror(errno));
}
}
if (data_exists) {
if(unlink(datafn)) {
fprintf(stderr, "Cache_exist(): unlink(): %s\n",
strerror(errno));
}
}
}
free(metafn);
free(datafn);
return !(meta_exists & data_exists);
}
Cache *Cache_create(const char *fn, long len, long time)
{
Cache *cf = Cache_alloc();
cf->filename = strndup(fn, MAX_PATH_LEN);
cf->time = time;
cf->len = len;
if (Data_create(cf)) {
Cache_free(cf);
fprintf(stderr, "Cache_create(): Data_create() failed!\n");
return NULL;
}
if (Meta_create(cf)) {
Cache_free(cf);
fprintf(stderr, "Cache_create(): Meta_create() failed!\n");
return NULL;
}
return cf;
}
void Cache_delete(const char *fn)
{
char *metafn = strndupcat(META_DIR, fn, MAX_PATH_LEN);
char *datafn = strndupcat(DATA_DIR, fn, MAX_PATH_LEN);
if (!access(metafn, F_OK)) {
if(unlink(metafn)) {
fprintf(stderr, "Cache_delete(): unlink(): %s\n",
/* Check if directories exist, if not, create them */
dir = opendir(META_DIR);
if (dir) {
closedir(dir);
} else if (mkdir(META_DIR, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH)) {
fprintf(stderr, "CacheSystem_init(): mkdir(): %s\n",
strerror(errno));
}
}
if (!access(datafn, F_OK)) {
if(unlink(datafn)) {
fprintf(stderr, "Cache_delete(): unlink(): %s\n",
strerror(errno));
}
dir = opendir(DATA_DIR);
if (dir) {
closedir(dir);
} else if (mkdir(META_DIR, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH)) {
fprintf(stderr, "CacheSystem_init(): mkdir(): %s\n",
strerror(errno));
}
free(metafn);
free(datafn);
}
Cache *Cache_open(const char *fn)
int Seg_exist(Cache *cf, long start)
{
/* Check if both metadata and data file exist */
if (Cache_validate(fn)) {
return NULL;
}
long total_bit = start / cf->blksz;
long byte = total_bit / 8;
int bit = total_bit % 8;
/* Create the cache in-memory data structure */
Cache *cf = Cache_alloc();
cf->filename = strndup(fn, MAX_PATH_LEN);
if (Meta_read(cf)) {
Cache_free(cf);
return NULL;
}
/* In consistent metadata / data file */
if (cf->len != Data_size(fn)) {
fprintf(stderr,
"Cache_open(): metadata is inconsistent with the data file!\n");
Cache_delete(fn);
Cache_free(cf);
return NULL;
}
return cf;
return cf->seg[byte] & (1 << bit);
}
int Meta_create(const Cache *cf)
void Seg_set(Cache *cf, long start, int i)
{
long total_bit = start / cf->blksz;
long byte = total_bit / 8;
int bit = total_bit % 8;
if (i) {
cf->seg[byte] |= (1 << bit);
} else {
cf->seg[byte] &= ~(1 << bit);
}
}
int Meta_create(Cache *cf)
{
cf->blksz = DATA_BLK_SZ;
cf->nseg = cf->len / cf->blksz + 1;
cf->seg = calloc(nseg, sizeof(Seg));
cf->segbc = cf->len / cf->blksz / 8 + 1;
cf->seg = calloc(cf->segbc, sizeof(Seg));
if (!(cf->seg)) {
fprintf(stderr, "Meta_create(): calloc failure!\n");
exit(EXIT_FAILURE);
@ -209,16 +138,16 @@ int Meta_read(Cache *cf)
fread(&(cf->time), sizeof(long), 1, fp);
fread(&(cf->len), sizeof(long), 1, fp);
fread(&(cf->len), sizeof(int), 1, fp);
fread(&(cf->nseg), sizeof(int), 1, fp);
fread(&(cf->segbc), sizeof(int), 1, fp);
/* Allocate some memory for the segment */
cf->seg = malloc(cf->nseg * sizeof(Seg));
cf->seg = malloc(cf->segbc * sizeof(Seg));
if (!(cf->seg)) {
fprintf(stderr, "Meta_read(): malloc failure!\n");
exit(EXIT_FAILURE);
}
/* Read all the segment */
nmemb = fread(cf->seg, sizeof(Seg), cf->nseg, fp);
nmemb = fread(cf->seg, sizeof(Seg), cf->segbc, fp);
/* Error checking for fread */
if (ferror(fp)) {
@ -228,10 +157,10 @@ int Meta_read(Cache *cf)
}
/* Check for inconsistent metadata file */
if (nmemb != cf-> nseg) {
if (nmemb != cf-> segbc) {
fprintf(stderr,
"Meta_read(): corrupted metadata!\n");
res = -1;
res = -2;
}
if (fclose(fp)) {
@ -258,8 +187,8 @@ int Meta_write(const Cache *cf)
fwrite(&(cf->time), sizeof(long), 1, fp);
fwrite(&(cf->len), sizeof(long), 1, fp);
fwrite(&(cf->blksz), sizeof(int), 1, fp);
fwrite(&(cf->nseg), sizeof(int), 1, fp);
fwrite(cf->seg, sizeof(Seg), cf->nseg, fp);
fwrite(&(cf->segbc), sizeof(int), 1, fp);
fwrite(cf->seg, sizeof(Seg), cf->segbc, fp);
/* Error checking for fwrite */
if (ferror(fp)) {
@ -408,3 +337,135 @@ long Data_write(const Cache *cf, long offset, long len,
}
return byte_written;
}
Cache *Cache_alloc()
{
Cache *cf = calloc(1, sizeof(Cache));
if (!cf) {
fprintf(stderr, "Cache_new(): calloc failure!\n");
exit(EXIT_FAILURE);
}
return cf;
}
void Cache_free(Cache *cf)
{
if (cf->filename) {
free(cf->filename);
}
if (cf->seg) {
free(cf->seg);
}
free(cf);
}
int Cache_exist(const char *fn)
{
int meta_exists = 1;
int data_exists = 1;
char *metafn = strndupcat(META_DIR, fn, MAX_PATH_LEN);
char *datafn = strndupcat(DATA_DIR, fn, MAX_PATH_LEN);
if (access(metafn, F_OK)) {
// fprintf(stderr, "Cache_exist(): access(): %s\n", strerror(errno));
meta_exists = 0;
}
if (access(datafn, F_OK)) {
// fprintf(stderr, "Cache_exist(): access(): %s\n", strerror(errno));
data_exists = 0;
}
if (meta_exists ^ data_exists) {
if (meta_exists) {
if(unlink(metafn)) {
fprintf(stderr, "Cache_exist(): unlink(): %s\n",
strerror(errno));
}
}
if (data_exists) {
if(unlink(datafn)) {
fprintf(stderr, "Cache_exist(): unlink(): %s\n",
strerror(errno));
}
}
}
free(metafn);
free(datafn);
return !(meta_exists & data_exists);
}
Cache *Cache_create(const char *fn, long len, long time)
{
Cache *cf = Cache_alloc();
cf->filename = strndup(fn, MAX_PATH_LEN);
cf->time = time;
cf->len = len;
if (Data_create(cf)) {
Cache_free(cf);
fprintf(stderr, "Cache_create(): Data_create() failed!\n");
return NULL;
}
if (Meta_create(cf)) {
Cache_free(cf);
fprintf(stderr, "Cache_create(): Meta_create() failed!\n");
return NULL;
}
return cf;
}
void Cache_delete(const char *fn)
{
char *metafn = strndupcat(META_DIR, fn, MAX_PATH_LEN);
char *datafn = strndupcat(DATA_DIR, fn, MAX_PATH_LEN);
if (!access(metafn, F_OK)) {
if(unlink(metafn)) {
fprintf(stderr, "Cache_delete(): unlink(): %s\n",
strerror(errno));
}
}
if (!access(datafn, F_OK)) {
if(unlink(datafn)) {
fprintf(stderr, "Cache_delete(): unlink(): %s\n",
strerror(errno));
}
}
free(metafn);
free(datafn);
}
Cache *Cache_open(const char *fn)
{
/* Check if both metadata and data file exist */
if (Cache_exist(fn)) {
return NULL;
}
/* Create the cache in-memory data structure */
Cache *cf = Cache_alloc();
cf->filename = strndup(fn, MAX_PATH_LEN);
/* Internal inconsistency metadata file */
if (Meta_read(cf) == -2) {
Cache_free(cf);
Cache_delete(fn);
return NULL;
}
/* Inconsistency between metadata and data file */
if (cf->len != Data_size(fn)) {
fprintf(stderr,
"Cache_open(): metadata is inconsistent with the data file!\n");
Cache_free(cf);
Cache_delete(fn);
return NULL;
}
return cf;
}

94
src/cache.h
View File

@ -16,7 +16,6 @@
* - CURLINFO_FILETIME
* - segment count (int)
* - individual segments (array of seg)
*
* \note
* - We are using 'long' to store file size, because the offset in fseek() is
* in long, because the way we use the cache system, you cannot seek past
@ -37,7 +36,7 @@ typedef struct {
long time; /**<the modified time of the file */
long len; /**<the size of the file */
int blksz; /**<the block size of the data file */
int nseg; /**<the number of segments */
long segbc; /**<segment array byte count */
Seg *seg; /**< the detail of each segment */
} Cache;
@ -60,66 +59,38 @@ long Cache_read(const char *fn, long offset, long len, uint8_t *buf);
long Cache_write(const char *fn, long offset, long len,
const uint8_t *buf);
/**
* \brief Initialise cache directory structure
*/
int Cache_DirInit(const char *fn);
/**
* \brief Create a directory within the cache structure
*/
int Cache_DirCreate(const char *fn);
int CacheDir_create(const char *fn);
/****************************** Work in progress *****************************/
/**************************** Completed functions ****************************/
/**
* \brief initialise the cache system
* \brief initialise the cache system directories
* \details This function basically sets up the following variables:
* - META_DIR
* - DATA_DIR
*
* If these directories do not exist, they will be created.
*/
void Cache_init(const char *dir);
void CacheSystem_init(const char *dir);
/**
* \brief Allocate a new cache data structure
* \brief Check if a segment exists.
*/
Cache *Cache_alloc();
int Seg_exist(Cache *cf, long start);
/**
* \brief free a cache data structure
* \brief Set the existence of a segment
* \param[in] start the starting position of the segment.
* \param[in] i 1 for exist, 0 for doesn't exist
*/
void Cache_free(Cache *cf);
void Seg_set(Cache *cf, long start, int i);
/**
* \brief Check if both metadata and data file exist, otherwise perform cleanup.
* \details
* This function checks if both metadata file and the data file exist. If that
* is not the case, clean up is performed - the existing unpaired metadata file
* or data file is deleted.
* \return
* - 0, if both metadata and cache file exist
* - -1, otherwise
*/
int Cache_exist(const char *fn);
/**
* \brief create a cache file set
*/
Cache *Cache_create(const char *fn, long len, long time);
/**
* \brief delete a cache file set
*/
void Cache_delete(const char *fn);
/**
* \brief open a cache file set
*/
Cache *Cache_open(const char *fn);
/**
* \brief create a metadata file
@ -131,7 +102,7 @@ Cache *Cache_open(const char *fn);
* 128KiB for now. In future support for different block size may be
* implemented.
*/
int Meta_create(const Cache *cf);
int Meta_create(Cache *cf);
/**
* \brief write a metadata file
@ -144,7 +115,8 @@ int Meta_write(const Cache *cf);
/**
* \brief read a metadata file
* \return
* - -1 on error,
* - -1 on fread error,
* - -2 on metadata internal inconsistency
* - 0 on success
*/
int Meta_read(Cache *cf);
@ -182,4 +154,40 @@ long Data_read(const Cache *cf, long offset, long len,
long Data_write(const Cache *cf, long offset, long len,
const uint8_t *buf);
/**
* \brief Allocate a new cache data structure
*/
Cache *Cache_alloc();
/**
* \brief free a cache data structure
*/
void Cache_free(Cache *cf);
/**
* \brief Check if both metadata and data file exist, otherwise perform cleanup.
* \details
* This function checks if both metadata file and the data file exist. If that
* is not the case, clean up is performed - the existing unpaired metadata file
* or data file is deleted.
* \return
* - 0, if both metadata and cache file exist
* - -1, otherwise
*/
int Cache_exist(const char *fn);
/**
* \brief create a cache file set
*/
Cache *Cache_create(const char *fn, long len, long time);
/**
* \brief delete a cache file set
*/
void Cache_delete(const char *fn);
/**
* \brief open a cache file set
*/
Cache *Cache_open(const char *fn);
#endif