backend init can now fail, and update media db when file is added

- Adding files inside Anki now updates the media DB, so a full file
scan at sync time is no longer required if no other changes have been
made.
- Use a protobuf message for backend initialization, and return a
string error if initialization fails.

proto/backend.proto

@@ -4,6 +4,12 @@ package backend_proto;
 
 message Empty {}
 
+message BackendInit {
+    string collection_path = 1;
+    string media_folder_path = 2;
+    string media_db_path = 3;
+}
+
 // 1-15 reserved for future use; 2047 for errors
 
 message BackendInput {

pylib/anki/media.py

@@ -23,8 +23,10 @@ from anki.latex import render_latex
 from anki.utils import checksum, isMac
 
 
-def media_folder_from_col_path(col_path: str) -> str:
-    return re.sub(r"(?i)\.(anki2)$", ".media", col_path)
+def media_paths_from_col_path(col_path: str) -> Tuple[str, str]:
+    media_folder = re.sub(r"(?i)\.(anki2)$", ".media", col_path)
+    media_db = media_folder + ".db2"
+    return (media_folder, media_db)
 
 
 class MediaManager:
@@ -45,7 +47,7 @@ class MediaManager:
             self._dir = None
             return
         # media directory
-        self._dir = media_folder_from_col_path(self.col.path)
+        self._dir = media_paths_from_col_path(self.col.path)[0]
         if not os.path.exists(self._dir):
             os.makedirs(self._dir)
         try:
@@ -63,7 +65,7 @@ class MediaManager:
     def connect(self) -> None:
         if self.col.server:
             return
-        path = self.dir() + ".db2"
+        path = media_paths_from_col_path(self.col.path)[1]
         create = not os.path.exists(path)
         os.chdir(self._dir)
         self.db = DB(path)

pylib/anki/rsbackend.py

@@ -90,8 +90,13 @@ def proto_replacement_list_to_native(
 
 
 class RustBackend:
-    def __init__(self, col_path: str, media_folder: str):
-        self._backend = ankirspy.Backend(col_path, media_folder)
+    def __init__(self, col_path: str, media_folder_path: str, media_db_path: str):
+        init_msg = pb.BackendInit(
+            collection_path=col_path,
+            media_folder_path=media_folder_path,
+            media_db_path=media_db_path,
+        )
+        self._backend = ankirspy.Backend(init_msg.SerializeToString())
 
     def _run_command(self, input: pb.BackendInput) -> pb.BackendOutput:
         input_bytes = input.SerializeToString()

pylib/anki/storage.py

@@ -11,7 +11,7 @@ from anki.collection import _Collection
 from anki.consts import *
 from anki.db import DB
 from anki.lang import _
-from anki.media import media_folder_from_col_path
+from anki.media import media_paths_from_col_path
 from anki.rsbackend import RustBackend
 from anki.stdmodels import (
     addBasicModel,
@@ -31,8 +31,9 @@ def Collection(
     path: str, lock: bool = True, server: Optional[ServerData] = None, log: bool = False
 ) -> _Collection:
     "Open a new or existing collection. Path must be unicode."
-    backend = RustBackend(path, media_folder_from_col_path(path))
     assert path.endswith(".anki2")
+    (media_dir, media_db) = media_paths_from_col_path(path)
+    backend = RustBackend(path, media_dir, media_db)
     path = os.path.abspath(path)
     create = not os.path.exists(path)
     if create:

rslib/src/backend.rs

@@ -6,7 +6,7 @@ use crate::backend_proto::backend_input::Value;
 use crate::backend_proto::RenderedTemplateReplacement;
 use crate::cloze::expand_clozes_to_reveal_latex;
 use crate::err::{AnkiError, Result};
-use crate::media::files::add_data_to_folder_uniquely;
+use crate::media::MediaManager;
 use crate::sched::{local_minutes_west_for_stamp, sched_timing_today};
 use crate::template::{
     render_card, without_legacy_template_directives, FieldMap, FieldRequirements, ParsedTemplate,
@@ -20,7 +20,7 @@ use std::path::PathBuf;
 pub struct Backend {
     #[allow(dead_code)]
     col_path: PathBuf,
-    media_folder: PathBuf,
+    media_manager: Option<MediaManager>,
 }
 
 /// Convert an Anki error to a protobuf error.
@@ -47,12 +47,33 @@ impl std::convert::From<AnkiError> for pt::backend_output::Value {
     }
 }
 
+pub fn init_backend(init_msg: &[u8]) -> std::result::Result<Backend, String> {
+    let input: pt::BackendInit = match pt::BackendInit::decode(init_msg) {
+        Ok(req) => req,
+        Err(_) => return Err("couldn't decode init request".into()),
+    };
+
+    match Backend::new(
+        &input.collection_path,
+        &input.media_folder_path,
+        &input.media_db_path,
+    ) {
+        Ok(backend) => Ok(backend),
+        Err(e) => Err(format!("{:?}", e)),
+    }
+}
+
 impl Backend {
-    pub fn new<P: Into<PathBuf>>(col_path: P, media_folder: P) -> Backend {
-        Backend {
+    pub fn new(col_path: &str, media_folder: &str, media_db: &str) -> Result<Backend> {
+        let media_manager = match (media_folder.is_empty(), media_db.is_empty()) {
+            (false, false) => Some(MediaManager::new(media_folder, media_db)?),
+            _ => None,
+        };
+
+        Ok(Backend {
             col_path: col_path.into(),
-            media_folder: media_folder.into(),
-        }
+            media_manager,
+        })
     }
 
     /// Decode a request, process it, and return the encoded result.
@@ -77,7 +98,7 @@ impl Backend {
         buf
     }
 
-    fn run_command(&self, input: pt::BackendInput) -> pt::BackendOutput {
+    fn run_command(&mut self, input: pt::BackendInput) -> pt::BackendOutput {
         let oval = if let Some(ival) = input.value {
             match self.run_command_inner(ival) {
                 Ok(output) => output,
@@ -91,7 +112,7 @@ impl Backend {
     }
 
     fn run_command_inner(
-        &self,
+        &mut self,
         ival: pt::backend_input::Value,
     ) -> Result<pt::backend_output::Value> {
         use pt::backend_output::Value as OValue;
@@ -230,11 +251,13 @@ impl Backend {
         }
     }
 
-    fn add_file_to_media_folder(&self, input: pt::AddFileToMediaFolderIn) -> Result<String> {
-        Ok(
-            add_data_to_folder_uniquely(&self.media_folder, &input.desired_name, &input.data)?
-                .into(),
-        )
+    fn add_file_to_media_folder(&mut self, input: pt::AddFileToMediaFolderIn) -> Result<String> {
+        Ok(self
+            .media_manager
+            .as_mut()
+            .unwrap()
+            .add_file(&input.desired_name, &input.data)?
+            .into())
     }
 }
 

rslib/src/media/database.rs

@@ -10,7 +10,6 @@ use std::path::Path;
 pub(super) fn open_or_create<P: AsRef<Path>>(path: P) -> Result<Connection> {
     let mut db = Connection::open(path)?;
 
-    db.pragma_update(None, "locking_mode", &"exclusive")?;
     db.pragma_update(None, "page_size", &4096)?;
     db.pragma_update(None, "legacy_file_format", &false)?;
     db.pragma_update(None, "journal", &"wal")?;

rslib/src/media/files.rs

@@ -93,6 +93,7 @@ pub fn add_data_to_folder_uniquely<'a, P>(
     folder: P,
     desired_name: &'a str,
     data: &[u8],
+    sha1: [u8; 20],
 ) -> io::Result<Cow<'a, str>>
 where
     P: AsRef<Path>,
@@ -108,14 +109,13 @@ where
         return Ok(normalized_name);
     }
 
-    let data_hash = sha1_of_data(data);
-    if existing_file_hash.unwrap() == data_hash {
+    if existing_file_hash.unwrap() == sha1 {
         // existing file has same checksum, nothing to do
         return Ok(normalized_name);
     }
 
     // give it a unique name based on its hash
-    let hashed_name = add_hash_suffix_to_file_stem(normalized_name.as_ref(), &data_hash);
+    let hashed_name = add_hash_suffix_to_file_stem(normalized_name.as_ref(), &sha1);
     target_path.set_file_name(&hashed_name);
 
     fs::write(&target_path, data)?;
@@ -233,7 +233,69 @@ struct FilesystemEntry {
     is_new: bool,
 }
 
+fn mtime_as_i64<P: AsRef<Path>>(path: P) -> io::Result<i64> {
+    Ok(path
+        .as_ref()
+        .metadata()?
+        .modified()?
+        .duration_since(time::UNIX_EPOCH)
+        .unwrap()
+        .as_secs() as i64)
+}
+
 impl MediaManager {
+    /// Add a file to the media folder.
+    ///
+    /// If a file with differing contents already exists, a hash will be
+    /// appended to the name.
+    ///
+    /// Also notes the file in the media database.
+    pub fn add_file<'a>(&mut self, desired_name: &'a str, data: &[u8]) -> Result<Cow<'a, str>> {
+        let pre_add_folder_mtime = mtime_as_i64(&self.media_folder)?;
+
+        // add file to folder
+        let data_hash = sha1_of_data(data);
+        let chosen_fname =
+            add_data_to_folder_uniquely(&self.media_folder, desired_name, data, data_hash)?;
+        let file_mtime = mtime_as_i64(self.media_folder.join(chosen_fname.as_ref()))?;
+        let post_add_folder_mtime = mtime_as_i64(&self.media_folder)?;
+
+        // add to the media DB
+        self.transact(|ctx| {
+            let existing_entry = ctx.get_entry(&chosen_fname)?;
+            let new_sha1 = Some(data_hash);
+
+            let entry_update_required = match existing_entry {
+                Some(existing) if existing.sha1 == new_sha1 => false,
+                _ => true,
+            };
+
+            if entry_update_required {
+                ctx.set_entry(&MediaEntry {
+                    fname: chosen_fname.to_string(),
+                    sha1: new_sha1,
+                    mtime: file_mtime,
+                    sync_required: true,
+                })?;
+            }
+
+            let mut meta = ctx.get_meta()?;
+            if meta.folder_mtime == pre_add_folder_mtime {
+                // if media db was in sync with folder prior to this add,
+                // we can keep it in sync
+                meta.folder_mtime = post_add_folder_mtime;
+                ctx.set_meta(&meta)?;
+            } else {
+                // otherwise, leave it alone so that other pending changes
+                // get picked up later
+            }
+
+            Ok(())
+        })?;
+
+        Ok(chosen_fname)
+    }
+
     /// Note any added/changed/deleted files.
     ///
     /// In the future, we could register files in the media DB as they
@@ -241,18 +303,12 @@ impl MediaManager {
     /// folder scan could be skipped.
     pub fn register_changes(&mut self) -> Result<()> {
         // folder mtime unchanged?
-        let media_dir_modified = self
-            .media_folder
-            .metadata()?
-            .modified()?
-            .duration_since(time::UNIX_EPOCH)
-            .unwrap()
-            .as_secs() as i64;
+        let dirmod = mtime_as_i64(&self.media_folder)?;
         let mut meta = self.get_meta()?;
-        if media_dir_modified == meta.folder_mtime {
+        if dirmod == meta.folder_mtime {
             return Ok(());
         } else {
-            meta.folder_mtime = media_dir_modified;
+            meta.folder_mtime = dirmod;
         }
 
         let mtimes = self.query(|ctx| ctx.all_mtimes())?;
@@ -438,20 +494,22 @@ mod test {
         let dpath = dir.path();
 
         // no existing file case
+        let h1 = sha1_of_data("hello".as_bytes());
         assert_eq!(
-            add_data_to_folder_uniquely(dpath, "test.mp3", "hello".as_bytes()).unwrap(),
+            add_data_to_folder_uniquely(dpath, "test.mp3", "hello".as_bytes(), h1).unwrap(),
             "test.mp3"
         );
 
         // same contents case
         assert_eq!(
-            add_data_to_folder_uniquely(dpath, "test.mp3", "hello".as_bytes()).unwrap(),
+            add_data_to_folder_uniquely(dpath, "test.mp3", "hello".as_bytes(), h1).unwrap(),
             "test.mp3"
         );
 
         // different contents
+        let h2 = sha1_of_data("hello1".as_bytes());
         assert_eq!(
-            add_data_to_folder_uniquely(dpath, "test.mp3", "hello1".as_bytes()).unwrap(),
+            add_data_to_folder_uniquely(dpath, "test.mp3", "hello1".as_bytes(), h2).unwrap(),
             "test-88fdd585121a4ccb3d1540527aee53a77c77abb8.mp3"
         );
 

rspy/src/lib.rs

@@ -1,7 +1,7 @@
-use anki::backend::Backend as RustBackend;
+use anki::backend::{init_backend, Backend as RustBackend};
 use pyo3::prelude::*;
 use pyo3::types::PyBytes;
-use pyo3::wrap_pyfunction;
+use pyo3::{exceptions, wrap_pyfunction};
 
 #[pyclass]
 struct Backend {
@@ -16,18 +16,20 @@ fn buildhash() -> &'static str {
 #[pymethods]
 impl Backend {
     #[new]
-    fn init(obj: &PyRawObject, col_path: String, media_folder: String) {
-        obj.init({
-            Backend {
-                backend: RustBackend::new(col_path, media_folder),
+    fn init(obj: &PyRawObject, init_msg: &PyBytes) -> PyResult<()> {
+        match init_backend(init_msg.as_bytes()) {
+            Ok(backend) => {
+                obj.init({ Backend { backend } });
+                Ok(())
             }
-        });
+            Err(e) => Err(exceptions::Exception::py_err(e)),
+        }
     }
 
-    fn command(&mut self, py: Python, input: &PyBytes) -> PyResult<PyObject> {
+    fn command(&mut self, py: Python, input: &PyBytes) -> PyObject {
         let out_bytes = self.backend.run_command_bytes(input.as_bytes());
         let out_obj = PyBytes::new(py, &out_bytes);
-        Ok(out_obj.into())
+        out_obj.into()
     }
 }