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优化内存分配

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This commit is contained in:
源文雨
2022-05-02 12:36:56 +08:00
parent 0196070fe0
commit e24f761f34
9 changed files with 129 additions and 105 deletions
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104
src/page.c
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@@ -2,7 +2,6 @@
// 管理文件中的空闲块
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
@@ -12,17 +11,14 @@
static const uint8_t nullpage[PAGESZ];
void* alloc_page(int fd) {
void* alloc_page(int fd, void* page) {
uint64_t ptr = 8, prev_ptr = 0, prev_prev_ptr = 0;
void* page;
uint8_t buf[8];
// 对于 page，只关心位于第一页 8~15 字节的 ptr of unused blk
while(ptr) {
if(!(ptr%PAGESZ)) { // 找到符合要求的页
if(lseek(fd, ptr, SEEK_SET) < 0) return NULL;
if(read(fd, buf, 8) != 8) return NULL;
page = malloc(PAGESZ+8);
if(page == NULL) return NULL;
putle64(page, ptr);
page += 8;
if(lseek(fd, prev_ptr, SEEK_SET) < 0) return NULL;
@@ -56,23 +52,16 @@ void* alloc_page(int fd) {
return NULL;
}
if(write(fd, nullpage, PAGESZ) != PAGESZ) return NULL;
page = malloc(PAGESZ+8);
if(page == NULL) return NULL;
putle64(page, ptr);
return page+8;
}
void* get_page(int fd, uint64_t ptr) {
void* get_page(int fd, uint64_t ptr, void* page) {
if(ptr%PAGESZ) return NULL;
if(lseek(fd, ptr, SEEK_SET) < 0) return NULL;
void* page = malloc(PAGESZ+8);
if(page == NULL) return NULL;
putle64(page, ptr);
page += 8;
if(read(fd, page, PAGESZ) != PAGESZ) {
free(page-8);
return NULL;
}
if(read(fd, page, PAGESZ) != PAGESZ) return NULL;
return page;
}
@@ -82,12 +71,6 @@ int sync_page(int fd, void* page) {
return write(fd, page, PAGESZ) != PAGESZ;
}
int unmount_page(int fd, void* page) {
int r = sync_page(fd, page);
free(page-8);
return r;
}
int free_page(int fd, void* page) {
uint64_t ptr = 8, prev_ptr = 0, prev_prev_ptr = 0, page_ptr = le64(page-8);
uint8_t buf[8];
@@ -119,13 +102,11 @@ int free_page(int fd, void* page) {
lseek(fd, prev_ptr, SEEK_SET);
if(write(fd, buf, 8) != 8) return EOF; // 将本页附加到链表
sync_page(fd, page);
free(page-8);
return 0;
}
void* alloc_block(int fd, uint16_t size) {
void* alloc_block(int fd, uint16_t size, void* blk) {
uint64_t ptr = 8, prev_ptr = 0, prev_prev_ptr = 0;
void* blk;
uint8_t buf[8];
uint16_t blksz;
@@ -136,8 +117,6 @@ void* alloc_block(int fd, uint16_t size) {
if(read(fd, buf, 8) != 8) return NULL;
readle16(fd, blksz);
if(blksz >= size) { // 找到符合要求的块
blk = malloc(size+10);
if(blk == NULL) return NULL;
if(blksz - size > 10) { // 分裂块
lseek(fd, ptr+size, SEEK_SET);
write(fd, buf, 8);
@@ -188,24 +167,17 @@ void* alloc_block(int fd, uint16_t size) {
putle16(buf, PAGESZ - size);
if(write(fd, buf, 2) != 2) return NULL;
}
blk = malloc(size+10);
if(blk == NULL) return NULL;
putle64(blk, ptr);
putle16(blk+8, size);
return blk+10;
}
void* get_block(int fd, uint16_t size, uint64_t ptr) {
void* get_block(int fd, uint16_t size, uint64_t ptr, void* blk) {
if(lseek(fd, ptr, SEEK_SET) < 0) return NULL;
void* blk = malloc(size+10);
if(blk == NULL) return NULL;
putle64(blk, ptr);
putle16(blk+8, size);
blk += 10;
if(read(fd, blk, size) != size) {
free(blk);
return NULL;
}
if(read(fd, blk, size) != size) return NULL;
return blk;
}
@@ -220,12 +192,6 @@ int sync_block(int fd, void* blk) {
return write(fd, blk, size) != size;
}
int unmount_block(int fd, void* blk) {
int r = sync_block(fd, blk);
free(blk-10);
return r;
}
int free_block(int fd, void* blk) {
uint64_t ptr = 8, prev_ptr = 0, prev_prev_ptr = 0, off = le64(blk-10);
uint8_t buf[8];
@@ -263,7 +229,6 @@ int free_block(int fd, void* blk) {
write(fd, blk, 8);
putle16(buf, size+sz);
write(fd, buf, 2);
free(blk-10);
return 0;
}
if(off+size == ptr && off%PAGESZ < ptr%PAGESZ) { // 可以和后一块合并
@@ -274,6 +239,61 @@ int free_block(int fd, void* blk) {
putle16(blk, size+sz);
}
sync_block(fd, blk);
free(blk-10);
return 0;
}
int add_block(int fd, uint16_t size, uint64_t off) {
uint64_t ptr = 8, prev_ptr = 0, prev_prev_ptr = 0;
uint8_t buf[8];
uint16_t sz;
while(ptr && ptr < off) {
if(prev_ptr == ptr) return EOF;
if(prev_prev_ptr && ptr < prev_ptr) { // 不符合顺序，进行一次调整
lseek(fd, prev_prev_ptr, SEEK_SET);
putle64(buf, ptr);
if(write(fd, buf, 8) != 8) return EOF; // 1->next = 3
if(lseek(fd, ptr, SEEK_SET) < 0) return EOF;
prev_prev_ptr = ptr; // new1 = 3
readle64(fd, ptr); // ptr(new3) = 3->next
lseek(fd, -8, SEEK_SET);
putle64(buf, prev_ptr); // new2 = 2
if(write(fd, buf, 8) != 8) return EOF; // 3->next = 2
lseek(fd, prev_ptr, SEEK_SET);
putle64(buf, ptr);
if(write(fd, buf, 8) != 8) return EOF; // 2->next = ptr
continue;
}
prev_prev_ptr = prev_ptr;
prev_ptr = ptr;
if(lseek(fd, ptr, SEEK_SET) < 0) return EOF;
readle64(fd, ptr);
}
if(lseek(fd, off, SEEK_SET) < 0) return EOF;
putle64(buf, ptr);
write(fd, buf, 8);
putle16(buf, size);
write(fd, buf, 2);
lseek(fd, prev_ptr, SEEK_SET);
putle64(buf, off);
if(write(fd, buf, 8) != 8) return EOF; // 将本页附加到链表
readle16(fd, sz);
if(prev_ptr+sz == off && prev_ptr%PAGESZ < off%PAGESZ) { // 可以和前一块合并
lseek(fd, prev_ptr, SEEK_SET);
putle64(buf, ptr);
write(fd, buf, 8);
putle16(buf, size+sz);
write(fd, buf, 2);
return 0;
}
if(off+size == ptr && off%PAGESZ < ptr%PAGESZ) { // 可以和后一块合并
if(lseek(fd, ptr, SEEK_SET) < 0) return EOF;
readle64(fd, prev_ptr);
readle16(fd, sz);
lseek(fd, off, SEEK_SET);
putle64(buf, prev_ptr);
write(fd, buf, 8);
putle16(buf, size+sz);
write(fd, buf, 2);
}
return 0;
}