mem_files.txt

mem_files.txt (2511B)
      1 MemFiles
      2 
      3 An in-memory, editable view of the single file on disk.
      4 
      5 The text is held in a `ropey::Rope` which is an in-memory file tree
      6 that allows cheap inserts and deletes without copying the whole
      7 buffer on every key stroke.
      8 
      9 `MemFile` is the thing an editing session mutates; disk only ever
     10 sees the results of a save.
     11 
     12 pub struct MemFile {
     13     /// The current text of the file, including any unsaved edits.
     14 	data: ropey::Rope,
     15 
     16     /// The path on disk this buffer reads from and writes back to.
     17 	path: std::path::PathBuf,
     18 
     19     /// Number of single character edits applied since the last save.
     20 	/// Reset to zero every time the buffer is flushed to disk.
     21 	ops_since_save: usize,
     22 }
     23 
     24 +--------+
     25 | user 1 |---------------+ 
     26 +--------+               |
     27                          |
     28 +--------+           +---------------+     +--------------+
     29 | user 2 |-----------| MemFile       |-----| file on disk |
     30 +--------+           | (ropey::Rope) |     +--------------+
     31                      +---------------+     (saves every 5 ops)
     32                          |
     33 +--------+               |
     34 | user 3 |---------------+
     35 +--------+
     36 
     37 *This works exactly like how the virtual DOM in React works.
     38 *ropey::Rope is a utf8 text rope. 
     39 
     40 
     41 ====================================================================
     42 
     43 The MemFileGuard owns everyfile an editing session has open in
     44 memory at once. 
     45 
     46 pub struct MemFileGuard {
     47     /// The live buffers, keyed by the path each one reads from
     48 	/// and writes back to. One entry per file currently open in
     49 	/// this session.
     50 	pub file_map: HashMap<std::path::PathBuf, MemFile>
     51 }
     52 
     53 ====================================================================
     54 
     55 How the actor gets spun up (the chain UP)
     56 
     57 WebSocket/HTTP API endpoint  (e.g. api/files/load.rs)
     58   └─→ Allocator actor                 git_management/actors/allocator/actor.rs
     59         └─→ register()                 allocator/processes/register.rs:48
     60               └─→ git_files_actor_constructor()   git_files/actor.rs:364
     61                     └─→ git_files_actor()  (the Tokio task)   actor.rs:42
     62                           └─→ MemFileGuard::default()         actor.rs:91
     63 
     64 When writing to MemFile:
     65 1. Loads a file from disk into a new in-memory buffer MemFile
     66 2. Insert it into the MemFileGuard
     67 3. Match on transaction's operation type (Insert/Delete/Swap)
     68 4. If its an insert, do insert_char or insert_text on the MemFile
     69 5. Finally, open up the file from disk, write to its buffer,
     70 	and then flush it to write to the OS.
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