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Revert back to single typed linked-list for opened mdirs

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While the multi per-type linked-lists were cool and could save RAM in
some structs (at the cost of RAM in the lfs_t struct), this is simpler,
and simpler is good.

The motivation to revert:

1. I noticed most file types have some sort of flags: files,
   traversals (future), (not dirs but maybe in the future). These flags
   can be merged with the type field to give us typed mdirs at almost
   no RAM cost.

2. Using a single linked-list makes it cheaper to add more file types,
   which may be useful for managing bookmarks (differently) and scratch
   files.

   This comes at a runtime cost, since all scans look at all opened
   structs, but we really, _really_ don't care about a constant non-IO
   runtime cost.

There are code benefits, since we don't need nested iterators to access
all opened mdirs, but also some code cost when we want to filter by
type. As expected stack took a small hit. Humorously, the struct savings
in lfs_t perfectly canceled out the struct hit to lfsr_dir_t:

            code          stack          structs
  before:  32992           2968             1080
  after:   33004 (+0.0%)   2976 (+0.3%)     1080 (+0.0%)
This commit is contained in:
Christopher Haster
2024-01-10 12:16:13 -06:00
parent da726c1376
commit dfdf109505
3 changed files with 312 additions and 346 deletions
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lfs.h
+26 -51
View File
@@ -116,39 +116,8 @@ enum lfs_error {
// File types
enum lfs_type {
// file types
LFS_TYPE_REG = 1,
LFS_TYPE_DIR = 2,
// used internally, don't use this
LFS_TYPE_INTERNAL = 3,
// // internally used types
// LFS_TYPE_SPLICE = 0x400,
// LFS_TYPE_NAME = 0x000,
// LFS_TYPE_STRUCT = 0x200,
// LFS_TYPE_USERATTR = 0x300,
// LFS_TYPE_FROM = 0x100,
// LFS_TYPE_TAIL = 0x600,
// LFS_TYPE_GLOBALS = 0x700,
// LFS_TYPE_CRC = 0x500,
//
// // internally used type specializations
// LFS_TYPE_CREATE = 0x401,
// LFS_TYPE_DELETE = 0x4ff,
// LFS_TYPE_SUPERBLOCK = 0x0ff,
// LFS_TYPE_DIRSTRUCT = 0x200,
// LFS_TYPE_CTZSTRUCT = 0x202,
// LFS_TYPE_INLINESTRUCT = 0x201,
// LFS_TYPE_SOFTTAIL = 0x600,
// LFS_TYPE_HARDTAIL = 0x601,
// LFS_TYPE_MOVESTATE = 0x7ff,
// LFS_TYPE_CCRC = 0x500,
// LFS_TYPE_FCRC = 0x5ff,
//
// // internal chip sources
// LFS_FROM_NOOP = 0x000,
// LFS_FROM_MOVE = 0x101,
// LFS_FROM_USERATTRS = 0x102,
LFS_TYPE_REG = 1,
LFS_TYPE_DIR = 2,
};
// File open flags
@@ -158,18 +127,18 @@ enum lfs_open_flags {
#ifndef LFS_READONLY
LFS_O_WRONLY = 2, // Open a file as write only
LFS_O_RDWR = 3, // Open a file as read and write
LFS_O_CREAT = 0x0100, // Create a file if it does not exist
LFS_O_EXCL = 0x0200, // Fail if a file already exists
LFS_O_TRUNC = 0x0400, // Truncate the existing file to zero size
LFS_O_APPEND = 0x0800, // Move to end of file on every write
LFS_O_SYNC = 0x1000, // Sync metadata on every write
LFS_O_DESYNC = 0x2000, // Do not sync or recieve file updates
LFS_O_FLUSH = 0x4000, // Flush data on every write
LFS_O_CREAT = 0x0004, // Create a file if it does not exist
LFS_O_EXCL = 0x0008, // Fail if a file already exists
LFS_O_TRUNC = 0x0010, // Truncate the existing file to zero size
LFS_O_APPEND = 0x0020, // Move to end of file on every write
LFS_O_SYNC = 0x0040, // Sync metadata on every write
LFS_O_DESYNC = 0x0080, // Do not sync or recieve file updates
LFS_O_FLUSH = 0x0100, // Flush data on every write
#endif
// internally used flags
LFS_F_UNFLUSHED = 0x010000, // File's data does not match storage
LFS_F_UNSYNCED = 0x020000, // File's metadata does not match storage
LFS_F_UNFLUSHED = 0x1000, // File's data does not match storage
LFS_F_UNSYNCED = 0x2000, // File's metadata does not match storage
};
// File seek flags
@@ -387,10 +356,12 @@ typedef struct lfsr_mdir {
lfsr_rbyd_t rbyd;
} lfsr_mdir_t;
typedef struct lfsr_openedmdir {
struct lfsr_openedmdir *next;
typedef struct lfsr_opened {
struct lfsr_opened *next;
uint8_t type;
uint16_t flags;
lfsr_mdir_t mdir;
} lfsr_openedmdir_t;
} lfsr_opened_t;
// space for:
// - type - 1 leb128 - 1 byte (worst case)
@@ -476,8 +447,11 @@ typedef struct lfs_dir {
} lfs_dir_t;
typedef struct lfsr_dir {
lfsr_openedmdir_t *next;
struct lfsr_opened *next;
uint8_t type;
uint16_t flags; // unused
lfsr_mdir_t mdir;
lfsr_did_t did;
lfsr_smid_t bookmark;
lfs_soff_t pos;
@@ -545,13 +519,15 @@ typedef struct lfsr_ftree {
} lfsr_ftree_t;
typedef struct lfsr_file {
lfsr_openedmdir_t *next;
struct lfsr_opened *next;
uint8_t type;
uint16_t flags;
lfsr_mdir_t mdir;
// files contain both an active tree and staging tree, to allow
// staging during mdir compacts
lfsr_ftree_t ftree;
lfsr_ftree_t ftree_;
uint32_t flags;
lfs_off_t pos;
lfs_off_t buffer_pos;
@@ -633,9 +609,8 @@ typedef struct lfs {
lfsr_mdir_t mroot;
lfsr_mtree_t mtree;
// linked-lists of opened mdirs, we keep a separate linked-list
// for each type since these need to be handled a bit differently
lfsr_openedmdir_t *opened[3];
// linked-list of opened mdirs
lfsr_opened_t *opened;
#ifdef LFS_MIGRATE
struct lfs1 *lfs1;