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borg/borg/_hashindex.c

380 lines
11 KiB
C
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#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#if defined(BYTE_ORDER)&&(BYTE_ORDER == BIG_ENDIAN)
#define _le32toh(x) __builtin_bswap32(x)
#define _htole32(x) __builtin_bswap32(x)
#elif defined(BYTE_ORDER)&&(BYTE_ORDER == LITTLE_ENDIAN)
#define _le32toh(x) (x)
#define _htole32(x) (x)
#else
#error Unknown byte order
#endif
typedef struct {
char magic[8];
int32_t num_entries;
int32_t num_buckets;
int8_t key_size;
int8_t value_size;
} __attribute__((__packed__)) HashHeader;
typedef struct {
void *buckets;
int num_entries;
int num_buckets;
int key_size;
int value_size;
off_t bucket_size;
int lower_limit;
int upper_limit;
} HashIndex;
#define MAGIC "BORG_IDX"
#define EMPTY _htole32(0xffffffff)
#define DELETED _htole32(0xfffffffe)
#define MAX_BUCKET_SIZE 512
#define BUCKET_LOWER_LIMIT .25
#define BUCKET_UPPER_LIMIT .90
#define MIN_BUCKETS 1024
#define MAX(x, y) ((x) > (y) ? (x): (y))
#define BUCKET_ADDR(index, idx) (index->buckets + (idx * index->bucket_size))
#define BUCKET_IS_DELETED(index, idx) (*((uint32_t *)(BUCKET_ADDR(index, idx) + index->key_size)) == DELETED)
#define BUCKET_IS_EMPTY(index, idx) (*((uint32_t *)(BUCKET_ADDR(index, idx) + index->key_size)) == EMPTY)
#define BUCKET_MATCHES_KEY(index, idx, key) (memcmp(key, BUCKET_ADDR(index, idx), index->key_size) == 0)
#define BUCKET_MARK_DELETED(index, idx) (*((uint32_t *)(BUCKET_ADDR(index, idx) + index->key_size)) = DELETED)
#define BUCKET_MARK_EMPTY(index, idx) (*((uint32_t *)(BUCKET_ADDR(index, idx) + index->key_size)) = EMPTY)
#define EPRINTF_MSG(msg, ...) fprintf(stderr, "hashindex: " msg "\n", ##__VA_ARGS__)
#define EPRINTF_MSG_PATH(path, msg, ...) fprintf(stderr, "hashindex: %s: " msg "\n", path, ##__VA_ARGS__)
#define EPRINTF(msg, ...) fprintf(stderr, "hashindex: " msg "(%s)\n", ##__VA_ARGS__, strerror(errno))
#define EPRINTF_PATH(path, msg, ...) fprintf(stderr, "hashindex: %s: " msg " (%s)\n", path, ##__VA_ARGS__, strerror(errno))
static HashIndex *hashindex_read(const char *path);
static int hashindex_write(HashIndex *index, const char *path);
static HashIndex *hashindex_init(int capacity, int key_size, int value_size);
static const void *hashindex_get(HashIndex *index, const void *key);
static int hashindex_set(HashIndex *index, const void *key, const void *value);
static int hashindex_delete(HashIndex *index, const void *key);
static void *hashindex_next_key(HashIndex *index, const void *key);
/* Private API */
static int
hashindex_index(HashIndex *index, const void *key)
{
return _le32toh(*((uint32_t *)key)) % index->num_buckets;
}
static int
hashindex_lookup(HashIndex *index, const void *key)
{
int didx = -1;
int start = hashindex_index(index, key);
int idx = start;
for(;;) {
if(BUCKET_IS_EMPTY(index, idx))
{
return -1;
}
if(BUCKET_IS_DELETED(index, idx)) {
if(didx == -1) {
didx = idx;
}
}
else if(BUCKET_MATCHES_KEY(index, idx, key)) {
if (didx != -1) {
memcpy(BUCKET_ADDR(index, didx), BUCKET_ADDR(index, idx), index->bucket_size);
BUCKET_MARK_DELETED(index, idx);
idx = didx;
}
return idx;
}
idx = (idx + 1) % index->num_buckets;
if(idx == start) {
return -1;
}
}
}
static int
hashindex_resize(HashIndex *index, int capacity)
{
HashIndex *new;
void *key = NULL;
if(!(new = hashindex_init(capacity, index->key_size, index->value_size))) {
return 0;
}
while((key = hashindex_next_key(index, key))) {
hashindex_set(new, key, hashindex_get(index, key));
}
free(index->buckets);
index->buckets = new->buckets;
index->num_buckets = new->num_buckets;
index->lower_limit = new->lower_limit;
index->upper_limit = new->upper_limit;
free(new);
return 1;
}
/* Public API */
static HashIndex *
hashindex_read(const char *path)
{
FILE *fd;
off_t length, buckets_length, bytes_read;
HashHeader header;
HashIndex *index = NULL;
if((fd = fopen(path, "rb")) == NULL) {
EPRINTF_PATH(path, "fopen for reading failed");
return NULL;
}
bytes_read = fread(&header, 1, sizeof(HashHeader), fd);
if(bytes_read != sizeof(HashHeader)) {
if(ferror(fd)) {
EPRINTF_PATH(path, "fread header failed (expected %ld, got %ld)", sizeof(HashHeader), bytes_read);
}
else {
EPRINTF_MSG_PATH(path, "fread header failed (expected %ld, got %ld)", sizeof(HashHeader), bytes_read);
}
goto fail;
}
if(fseek(fd, 0, SEEK_END) < 0) {
EPRINTF_PATH(path, "fseek failed");
goto fail;
}
if((length = ftell(fd)) < 0) {
EPRINTF_PATH(path, "ftell failed");
goto fail;
}
if(fseek(fd, sizeof(HashHeader), SEEK_SET) < 0) {
EPRINTF_PATH(path, "fseek failed");
goto fail;
}
if(memcmp(header.magic, MAGIC, 8)) {
EPRINTF_MSG_PATH(path, "Unknown MAGIC in header");
goto fail;
}
buckets_length = (off_t)_le32toh(header.num_buckets) * (header.key_size + header.value_size);
if(length != sizeof(HashHeader) + buckets_length) {
EPRINTF_MSG_PATH(path, "Incorrect file length (expected %ld, got %ld)", sizeof(HashHeader) + buckets_length, length);
goto fail;
}
if(!(index = malloc(sizeof(HashIndex)))) {
EPRINTF_PATH(path, "malloc header failed");
goto fail;
}
if(!(index->buckets = malloc(buckets_length))) {
EPRINTF_PATH(path, "malloc buckets failed");
free(index);
index = NULL;
goto fail;
}
bytes_read = fread(index->buckets, 1, buckets_length, fd);
if(bytes_read != buckets_length) {
if(ferror(fd)) {
EPRINTF_PATH(path, "fread buckets failed (expected %ld, got %ld)", buckets_length, bytes_read);
}
else {
EPRINTF_MSG_PATH(path, "fread buckets failed (expected %ld, got %ld)", buckets_length, bytes_read);
}
free(index->buckets);
free(index);
index = NULL;
goto fail;
}
index->num_entries = _le32toh(header.num_entries);
index->num_buckets = _le32toh(header.num_buckets);
index->key_size = header.key_size;
index->value_size = header.value_size;
index->bucket_size = index->key_size + index->value_size;
index->lower_limit = index->num_buckets > MIN_BUCKETS ? ((int)(index->num_buckets * BUCKET_LOWER_LIMIT)) : 0;
index->upper_limit = (int)(index->num_buckets * BUCKET_UPPER_LIMIT);
fail:
if(fclose(fd) < 0) {
EPRINTF_PATH(path, "fclose failed");
}
return index;
}
static HashIndex *
hashindex_init(int capacity, int key_size, int value_size)
{
off_t buckets_length;
HashIndex *index;
int i;
capacity = MAX(MIN_BUCKETS, capacity);
if(!(index = malloc(sizeof(HashIndex)))) {
EPRINTF("malloc header failed");
return NULL;
}
buckets_length = (off_t)capacity * (key_size + value_size);
if(!(index->buckets = calloc(buckets_length, 1))) {
EPRINTF("malloc buckets failed");
free(index);
return NULL;
}
index->num_entries = 0;
index->key_size = key_size;
index->value_size = value_size;
index->num_buckets = capacity;
index->bucket_size = index->key_size + index->value_size;
index->lower_limit = index->num_buckets > MIN_BUCKETS ? ((int)(index->num_buckets * BUCKET_LOWER_LIMIT)) : 0;
index->upper_limit = (int)(index->num_buckets * BUCKET_UPPER_LIMIT);
for(i = 0; i < capacity; i++) {
BUCKET_MARK_EMPTY(index, i);
}
return index;
}
static void
hashindex_free(HashIndex *index)
{
free(index->buckets);
free(index);
}
static int
hashindex_write(HashIndex *index, const char *path)
{
off_t buckets_length = (off_t)index->num_buckets * index->bucket_size;
FILE *fd;
HashHeader header = {
.magic = MAGIC,
.num_entries = _htole32(index->num_entries),
.num_buckets = _htole32(index->num_buckets),
.key_size = index->key_size,
.value_size = index->value_size
};
int ret = 1;
if((fd = fopen(path, "wb")) == NULL) {
EPRINTF_PATH(path, "fopen for writing failed");
return 0;
}
if(fwrite(&header, 1, sizeof(header), fd) != sizeof(header)) {
EPRINTF_PATH(path, "fwrite header failed");
ret = 0;
}
if(fwrite(index->buckets, 1, buckets_length, fd) != buckets_length) {
EPRINTF_PATH(path, "fwrite buckets failed");
ret = 0;
}
if(fclose(fd) < 0) {
EPRINTF_PATH(path, "fclose failed");
}
return ret;
}
static const void *
hashindex_get(HashIndex *index, const void *key)
{
int idx = hashindex_lookup(index, key);
if(idx < 0) {
return NULL;
}
return BUCKET_ADDR(index, idx) + index->key_size;
}
static int
hashindex_set(HashIndex *index, const void *key, const void *value)
{
int idx = hashindex_lookup(index, key);
uint8_t *ptr;
if(idx < 0)
{
if(index->num_entries > index->upper_limit) {
if(!hashindex_resize(index, index->num_buckets * 2)) {
return 0;
}
}
idx = hashindex_index(index, key);
while(!BUCKET_IS_EMPTY(index, idx) && !BUCKET_IS_DELETED(index, idx)) {
idx = (idx + 1) % index->num_buckets;
}
ptr = BUCKET_ADDR(index, idx);
memcpy(ptr, key, index->key_size);
memcpy(ptr + index->key_size, value, index->value_size);
index->num_entries += 1;
}
else
{
memcpy(BUCKET_ADDR(index, idx) + index->key_size, value, index->value_size);
}
return 1;
}
static int
hashindex_delete(HashIndex *index, const void *key)
{
int idx = hashindex_lookup(index, key);
if (idx < 0) {
return 1;
}
BUCKET_MARK_DELETED(index, idx);
index->num_entries -= 1;
if(index->num_entries < index->lower_limit) {
if(!hashindex_resize(index, index->num_buckets / 2)) {
return 0;
}
}
return 1;
}
static void *
hashindex_next_key(HashIndex *index, const void *key)
{
int idx = 0;
if(key) {
idx = 1 + (key - index->buckets) / index->bucket_size;
}
if (idx == index->num_buckets) {
return NULL;
}
while(BUCKET_IS_EMPTY(index, idx) || BUCKET_IS_DELETED(index, idx)) {
idx ++;
if (idx == index->num_buckets) {
return NULL;
}
}
return BUCKET_ADDR(index, idx);
}
static int
hashindex_get_size(HashIndex *index)
{
return index->num_entries;
}
static void
hashindex_summarize(HashIndex *index, long long *total_size, long long *total_csize, long long *total_unique_size, long long *total_unique_csize)
{
int64_t size = 0, csize = 0, unique_size = 0, unique_csize = 0;
const int32_t *values;
void *key = NULL;
while((key = hashindex_next_key(index, key))) {
values = key + index->key_size;
unique_size += values[1];
unique_csize += values[2];
size += values[0] * values[1];
csize += values[0] * values[2];
}
*total_size = size;
*total_csize = csize;
*total_unique_size = unique_size;
*total_unique_csize = unique_csize;
}
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