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Clarified and cleaned up Coffee's documentation and the debug statements. Formatted some source code for easier reading.

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This commit is contained in:
Nicolas Tsiftes 2016-04-20 14:30:20 +02:00
parent 7586195b79
commit 86733e8702
2 changed files with 56 additions and 62 deletions
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47
core/cfs/cfs-coffee.c
View file

@ -114,8 +114,7 @@
#define GC_RELUCTANT 1
/* File descriptor macros. */
#define FD_VALID(fd) \
((fd) >= 0 && (fd) < COFFEE_FD_SET_SIZE && \
#define FD_VALID(fd) ((fd) >= 0 && (fd) < COFFEE_FD_SET_SIZE && \
coffee_fd_set[(fd)].flags != COFFEE_FD_FREE)
#define FD_READABLE(fd) (coffee_fd_set[(fd)].flags & CFS_READ)
#define FD_WRITABLE(fd) (coffee_fd_set[(fd)].flags & CFS_WRITE)
@ -127,10 +126,10 @@
#define FILE_UNREFERENCED(file) ((file)->references == 0)
/* File header flags. */
#define HDR_FLAG_VALID 0x1 /* Completely written header. */
#define HDR_FLAG_ALLOCATED 0x2 /* Allocated file. */
#define HDR_FLAG_OBSOLETE 0x4 /* File marked for GC. */
#define HDR_FLAG_MODIFIED 0x8 /* Modified file, log exists. */
#define HDR_FLAG_VALID 0x01 /* Completely written header. */
#define HDR_FLAG_ALLOCATED 0x02 /* Allocated file. */
#define HDR_FLAG_OBSOLETE 0x04 /* File marked for GC. */
#define HDR_FLAG_MODIFIED 0x08 /* Modified file, log exists. */
#define HDR_FLAG_LOG 0x10 /* Log file. */
#define HDR_FLAG_ISOLATED 0x20 /* Isolated page. */
@ -148,7 +147,8 @@
!HDR_ISOLATED(hdr))
/* Shortcuts derived from the hardware-dependent configuration of Coffee. */
#define COFFEE_SECTOR_COUNT (unsigned)(COFFEE_SIZE / COFFEE_SECTOR_SIZE)
#define COFFEE_SECTOR_COUNT \
(coffee_page_t)(COFFEE_SIZE / COFFEE_SECTOR_SIZE)
#define COFFEE_PAGE_COUNT \
((coffee_page_t)(COFFEE_SIZE / COFFEE_PAGE_SIZE))
#define COFFEE_PAGES_PER_SECTOR \
@ -235,7 +235,7 @@ absolute_offset(coffee_page_t page, cfs_offset_t offset)
}
/*---------------------------------------------------------------------------*/
static coffee_page_t
get_sector_status(uint16_t sector, struct sector_status *stats)
get_sector_status(coffee_page_t sector, struct sector_status *stats)
{
static coffee_page_t skip_pages;
static char last_pages_are_active;
@ -305,7 +305,7 @@ get_sector_status(uint16_t sector, struct sector_status *stats)
/*
* Determine the amount of pages in the following sectors that
* should be remembered for the next iteration. This is necessary
* because no page except the first of a file contains information
* because no file page except the first contains information
* about what type of page it is. A side effect of remembering this
* amount is that there is no need to read in the headers of each
* of these pages from the storage.
@ -356,11 +356,11 @@ isolate_pages(coffee_page_t start, coffee_page_t skip_pages)
static void
collect_garbage(int mode)
{
uint16_t sector;
coffee_page_t sector;
struct sector_status stats;
coffee_page_t first_page, isolation_count;
PRINTF("Coffee: Running the file system garbage collector in %s mode\n",
PRINTF("Coffee: Running the garbage collector in %s mode\n",
mode == GC_RELUCTANT ? "reluctant" : "greedy");
/*
* The garbage collector erases as many sectors as possible. A sector is
@ -369,7 +369,7 @@ collect_garbage(int mode)
for(sector = 0; sector < COFFEE_SECTOR_COUNT; sector++) {
isolation_count = get_sector_status(sector, &stats);
PRINTF("Coffee: Sector %u has %u active, %u obsolete, and %u free pages.\n",
sector, (unsigned)stats.active,
(unsigned)sector, (unsigned)stats.active,
(unsigned)stats.obsolete, (unsigned)stats.free);
if(stats.active > 0) {
@ -402,7 +402,7 @@ next_file(coffee_page_t page, struct file_header *hdr)
{
/*
* The quick-skip algorithm for finding file extents is the most
* essential part of Coffee. The file allocation rules enables this
* essential part of Coffee. The file allocation rules enable this
* algorithm to quickly jump over free areas and allocated extents
* after reading single headers and determining their status.
*
@ -648,7 +648,7 @@ reserve(const char *name, coffee_page_t pages,
write_header(&hdr, page);
PRINTF("Coffee: Reserved %u pages starting from %u for file %s\n",
pages, page, name);
(unsigned)pages, (unsigned)page, name);
file = load_file(page, &hdr);
if(file != NULL) {
@ -843,7 +843,7 @@ merge_log(coffee_page_t file_page, int extend)
return -1;
}
/* Copy the log configuration and the EOF hint. */
/* Copy the log configuration. */
read_header(&hdr2, new_file->page);
hdr2.log_record_size = hdr.log_record_size;
hdr2.log_records = hdr.log_records;
@ -1102,7 +1102,7 @@ cfs_read(int fd, void *buf, unsigned size)
size = file->end - fdp->offset;
}
/* If the file is allocated, read directly in the file. */
/* If the file is not modified, read directly from the file extent. */
if(!FILE_MODIFIED(file)) {
COFFEE_READ(buf, size, absolute_offset(file->page, fdp->offset));
fdp->offset += size;
@ -1113,8 +1113,9 @@ cfs_read(int fd, void *buf, unsigned size)
read_header(&hdr, file->page);
/*
* Fill the buffer by copying from the log in first hand, or the
* ordinary file if the page has no log record.
* Copy the contents of the most recent log record. If there is
* no log record for the file area to read from, we simply read
* from the original file extent.
*/
for(bytes_left = size; bytes_left > 0; bytes_left -= r) {
lp.offset = fdp->offset;
@ -1242,8 +1243,8 @@ int
cfs_opendir(struct cfs_dir *dir, const char *name)
{
/*
* Coffee is only guaranteed to support "/" and ".", but it does not
* currently enforce this.
* Coffee is only guaranteed to support the directory names "/" and ".",
* but it does not enforce this currently.
*/
memset(dir->dummy_space, 0, sizeof(coffee_page_t));
return 0;
@ -1254,13 +1255,13 @@ cfs_readdir(struct cfs_dir *dir, struct cfs_dirent *record)
{
struct file_header hdr;
coffee_page_t page;
coffee_page_t next_page;
memcpy(&page, dir->dummy_space, sizeof(coffee_page_t));
while(page < COFFEE_PAGE_COUNT) {
read_header(&hdr, page);
if(HDR_ACTIVE(hdr) && !HDR_LOG(hdr)) {
coffee_page_t next_page;
memcpy(record->name, hdr.name, sizeof(record->name));
record->name[sizeof(record->name) - 1] = '\0';
record->size = file_end(page);
@ -1334,9 +1335,9 @@ cfs_coffee_set_io_semantics(int fd, unsigned flags)
int
cfs_coffee_format(void)
{
unsigned i;
coffee_page_t i;
PRINTF("Coffee: Formatting %u sectors", COFFEE_SECTOR_COUNT);
PRINTF("Coffee: Formatting %u sectors", (unsigned)COFFEE_SECTOR_COUNT);
for(i = 0; i < COFFEE_SECTOR_COUNT; i++) {
COFFEE_ERASE(i);

41
core/cfs/cfs-coffee.h
View file

@ -46,15 +46,15 @@
* invoke its own micro logs when file modifications occur.
*
* This semantical I/O setting is useful when implementing flash storage
* algorithms on top of Coffee.
* algorithms such as database indices on top of Coffee.
*
* \sa cfs_coffee_set_io_semantics()
*/
#define CFS_COFFEE_IO_FLASH_AWARE 0x1
/**
* Instruct Coffee not to attempt to extend the file when there is
* an attempt to write past the reserved file size.
* Instruct Coffee not to attempt to extend the file upon a request
* to write past the reserved file size.
*
* A case when this is necessary is when the file has a firm size limit,
* and a safeguard is needed to protect against writes beyond this limit.
@ -75,8 +75,8 @@
/**
* \brief Reserve space for a file.
* \param name The filename.
* \param size The size of the file.
* \param name The file name.
* \param size The initial size to be reserved for the file.
* \return 0 on success, -1 on failure.
*
* Coffee uses sequential page structures for files. The sequential
@ -88,15 +88,15 @@ int cfs_coffee_reserve(const char *name, cfs_offset_t size);
/**
* \brief Configure the on-demand log file.
* \param file The filename.
* \param log_size The total log size.
* \param file The file name.
* \param log_size The total log file size.
* \param log_entry_size The log entry size.
* \return 0 on success, -1 on failure.
*
* When file data is first modified, Coffee creates a micro log for the
* file. The micro log stores a table of modifications whose
* parameters--the log size and the log entry size--can be modified
* through the cfs_coffee_configure_log function.
* file. The micro log stores a table of modifications whose parameters --
* the log size and the log entry size -- can be modified through the
* cfs_coffee_configure_log function.
*/
int cfs_coffee_configure_log(const char *file, unsigned log_size,
unsigned log_entry_size);
@ -109,8 +109,8 @@ int cfs_coffee_configure_log(const char *file, unsigned log_size,
*
* Coffee is used on a wide range of storage types, and the default
* I/O file semantics may not be optimal for the access pattern
* of a certain file. Hence, this functions allows programmers to
* switch the /O semantics on a file that is accessed through a
* of a certain file. Hence, this function allows programmers to
* switch the I/O semantics on a file that is accessed through a
* particular file descriptor.
*
*/
@ -123,21 +123,14 @@ int cfs_coffee_set_io_semantics(int fd, unsigned flags);
* Coffee formats the underlying storage by setting all bits to zero.
* Formatting must be done before using Coffee for the first time in
* a mote.
*
* Notice that the erased bits may be set to 1 on the physical storage
* when using flash memory. In this case, Coffee requires that the
* COFFEE_READ and COFFEE_WRITE functions used to access the flash memory
* invert all bits.
*/
int cfs_coffee_format(void);
/**
* \brief Points out a memory region that may not be altered during
* checkpointing operations that use the file system.
* \param size
* \return A pointer to the protected memory.
*
* This function returns the protected memory pointer and writes its size
* to the given parameter. Mainly used by sensornet checkpointing to protect
* the coffee state during CFS-based checkpointing operations.
*/
void *cfs_coffee_get_protected_mem(unsigned *size);
/** @} */
/** @} */