Snapshot: V4 plugin API and host integration

crates/ocs_plugin_api/src/host_v4.rs

@@ -0,0 +1,91 @@
+//! Host-side V4 snapshot manager.
+//!
+//! Maintains a per-tab shared-memory document view keyed by the stable
+//! `DocumentTab.id`. The manager is used by `src/plugin/v4_support.rs` to
+//! open, publish, and close V4 snapshots independently of the V3 reader path.
+
+use std::collections::HashMap;
+use std::sync::{Mutex, OnceLock};
+
+use acadrust::CadDocument;
+
+use crate::shm::{DocumentSnapshotStore, DocumentViewDataV4, DocumentViewInfo};
+
+static MANAGER: OnceLock<Mutex<HostV4SnapshotManager>> = OnceLock::new();
+
+fn global_manager() -> &'static Mutex<HostV4SnapshotManager> {
+    MANAGER.get_or_init(|| Mutex::new(HostV4SnapshotManager::new()))
+}
+
+/// Per-tab V4 shared-memory snapshot manager.
+pub struct HostV4SnapshotManager {
+    stores: HashMap<u64, DocumentSnapshotStore<DocumentViewDataV4>>,
+    segment_size: usize,
+}
+
+impl HostV4SnapshotManager {
+    /// Create a new manager with the default segment size.
+    pub fn new() -> Self {
+        Self {
+            stores: HashMap::new(),
+            segment_size: default_segment_size(),
+        }
+    }
+
+    /// Open (or refresh) the V4 snapshot for `tab_id` and return the view info.
+    pub fn open(&mut self, tab_id: u64, doc: &CadDocument) -> Option<DocumentViewInfo> {
+        let store = match self.stores.get_mut(&tab_id) {
+            Some(store) => store,
+            None => {
+                let store = DocumentSnapshotStore::new(tab_id, self.segment_size).ok()?;
+                self.stores.entry(tab_id).or_insert(store)
+            }
+        };
+        if let Err(e) = store.publish(&doc.into()) {
+            eprintln!("[host] failed to publish V4 document view for tab {tab_id}: {e}");
+            return None;
+        }
+        Some(DocumentViewInfo {
+            path: store.path().to_string_lossy().into_owned(),
+            version: store.version(),
+        })
+    }
+
+    /// Publish the latest document to the existing V4 snapshot for `tab_id`.
+    /// Returns the updated view info if the snapshot exists.
+    pub fn publish(&mut self, tab_id: u64, doc: &CadDocument) -> Option<DocumentViewInfo> {
+        let store = self.stores.get_mut(&tab_id)?;
+        if let Err(e) = store.publish(&doc.into()) {
+            eprintln!("[host] failed to publish V4 document view for tab {tab_id}: {e}");
+            return None;
+        }
+        Some(DocumentViewInfo {
+            path: store.path().to_string_lossy().into_owned(),
+            version: store.version(),
+        })
+    }
+
+    /// Close the V4 snapshot for `tab_id`.
+    pub fn close(&mut self, tab_id: u64) {
+        self.stores.remove(&tab_id);
+    }
+}
+
+impl Default for HostV4SnapshotManager {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+/// Global accessor for the host V4 snapshot manager.
+pub fn manager() -> &'static Mutex<HostV4SnapshotManager> {
+    global_manager()
+}
+
+fn default_segment_size() -> usize {
+    std::env::var("OCS_V4_SNAPSHOT_SEGMENT_SIZE")
+        .ok()
+        .and_then(|s| s.parse().ok())
+        .unwrap_or(16 * 1024 * 1024)
+        .max(1024 * 1024)
+}