wasm: read the clock through one helper, and test a commit on wasm32

.github/workflows/test.yml

@@ -262,6 +262,39 @@ jobs:
       - name: cargo check --lib
         run: cargo check -p pagedb --target ${{ matrix.target }} --lib ${{ matrix.features }}
 
+  # ─────────────────────────────────────────────────────────────────────────
+  # Runtime wasm coverage. The `wasm` job above only compiles: a wall-clock
+  # read inside the txn layer compiles fine on wasm32 and panics at the first
+  # commit ("time not implemented on this platform"), which is invisible to a
+  # check. This job runs the smoke crate under node.
+  wasm-tests:
+    name: WASM / node smoke (wasm32)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+
+      - name: Install Rust + target
+        uses: dtolnay/rust-toolchain@4cda84d5c5c54efe2404f9d843567869ab1699d4 # stable
+        with:
+          targets: wasm32-unknown-unknown
+
+      - uses: Swatinem/rust-cache@6323deb102c322ba6fcbdcafc7e3dddab59af2b6 # v2.9.2
+        with:
+          prefix-key: wasm-smoke
+
+      # The runner must match the wasm-bindgen version the lockfile resolves,
+      # so read it from `cargo metadata` instead of pinning a number here.
+      - name: Install wasm-bindgen-test-runner
+        run: |
+          version=$(cargo metadata --format-version 1 --locked \
+            | python3 -c "import json,sys; d=json.load(sys.stdin); print(next(p['version'] for p in d['packages'] if p['name']=='wasm-bindgen'))")
+          cargo install wasm-bindgen-cli --version "$version" --locked
+
+      - name: Run wasm smoke tests (node)
+        env:
+          CARGO_TARGET_WASM32_UNKNOWN_UNKNOWN_RUNNER: wasm-bindgen-test-runner
+        run: cargo test -p pagedb-wasm-smoke --target wasm32-unknown-unknown --test commit_smoke
+
   # ─────────────────────────────────────────────────────────────────────────
   features:
     name: Feature matrix (${{ matrix.flags }})

CHANGELOG.md

@@ -21,6 +21,10 @@ No version has been released yet. Pre-releases are published as `0.1.0-beta.N`;
 - **Open refusals name the parameter, not the store** — `KeyMismatch`, `PageSizeMismatch`, and `RealmMismatch`, each decided before anything is read or written, and none reported as corruption.
 - **Failures report themselves** — an unreadable free-list chain, main file, or segment catalog fails `stats()` instead of reporting zero; compaction never skips a catalog entry whose file it cannot open; segment open distinguishes a missing file from a permission or backend error; and only genuine contention is reported as contention. Persisted named-counter rows are validated at open, and commit-history keys are rejected unless exactly eight bytes.
 
+### Fixed
+
+- **Commits no longer need a wall clock.** `WriteTxn::commit` and the age-based retention threshold read `SystemTime::now()` directly, which panics on `wasm32-unknown-unknown` ("time not implemented on this platform") — the first write from an embedded build failed. Both go through `clock::unix_seconds()` now: `js_sys::Date::now()` on the OPFS build, std elsewhere, and `0` for a wasm build without the JS bindings instead of a panic. `wasm-smoke/` commits once per policy under node so the target stays covered.
+
 ### Security
 
 - Threat model documented in the README; disclosure policy in `SECURITY.md`.

Cargo.toml

@@ -1,5 +1,5 @@
 [workspace]
-members = ["benchmarks/engine-comparison"]
+members = ["benchmarks/engine-comparison", "wasm-smoke"]
 default-members = ["."]
 resolver = "3"
 
@@ -132,6 +132,9 @@ opfs = [
     "dep:futures",
 ]
 
+[target.'cfg(all(target_arch = "wasm32", target_os = "unknown"))'.dev-dependencies]
+wasm-bindgen-test = "0.3"
+
 [dev-dependencies]
 tokio = { version = "1", features = [
     "rt",

src/btree/tree/core.rs

@@ -620,15 +620,21 @@ mod tests {
             tree.free_page(id);
         }
 
+        // The loop is functional coverage on every target; the bound is a
+        // wall-clock regression guard, so it only runs where a clock exists.
+        #[cfg(not(all(target_arch = "wasm32", target_os = "unknown")))]
         let start = std::time::Instant::now();
         for _ in 0..N {
             tree.allocate_page();
         }
-        let elapsed = start.elapsed();
-        assert!(
-            elapsed < std::time::Duration::from_secs(10),
-            "{N} allocations against {N} held-back frees took {elapsed:?} — \
-             allocation is scanning the freed list again"
-        );
+        #[cfg(not(all(target_arch = "wasm32", target_os = "unknown")))]
+        {
+            let elapsed = start.elapsed();
+            assert!(
+                elapsed < std::time::Duration::from_secs(10),
+                "{N} allocations against {N} held-back frees took {elapsed:?} — \
+                 allocation is scanning the freed list again"
+            );
+        }
     }
 }

src/clock.rs

@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+//! Wall-clock access.
+//!
+//! `wasm32-unknown-unknown` has no std clock: `SystemTime::now()` panics with
+//! "time not implemented on this platform". The OPFS build reads the host
+//! clock through `js_sys` instead; a wasm build without that feature degrades
+//! to `0` rather than panicking. Every other target, `wasm32-wasip1`
+//! included, uses std.
+
+/// Seconds since the Unix epoch.
+///
+/// Feeds the commit-history timestamp and the age-based retention threshold.
+/// A `0` (no clock in this configuration) keeps both ordered by commit
+/// sequence instead of inventing a time.
+#[cfg(all(target_arch = "wasm32", target_os = "unknown", feature = "opfs"))]
+pub(crate) fn unix_seconds() -> u64 {
+    (js_sys::Date::now() / 1000.0) as u64
+}
+
+/// No clock in this configuration: `wasm32-unknown-unknown` without the JS
+/// bindings. Callers get `0`, which the commit-history ordering tolerates.
+#[cfg(all(target_arch = "wasm32", target_os = "unknown", not(feature = "opfs")))]
+pub(crate) fn unix_seconds() -> u64 {
+    0
+}
+
+#[cfg(not(all(target_arch = "wasm32", target_os = "unknown")))]
+pub(crate) fn unix_seconds() -> u64 {
+    std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .map_or(0, |d| d.as_secs())
+}

src/lib.rs

@@ -16,6 +16,7 @@
 // must not be able to reach around.
 pub(crate) mod btree;
 pub(crate) mod catalog;
+pub(crate) mod clock;
 pub(crate) mod compaction;
 pub(crate) mod crypto;
 pub(crate) mod diag;

src/txn/db/catalog/history.rs

@@ -148,9 +148,7 @@ impl<V: Vfs + Clone> Db<V> {
                 state.commit_history_count = Some(total.saturating_sub(deleted));
             }
             crate::options::RetainPolicy::Age(duration) => {
-                let now_secs = std::time::SystemTime::now()
-                    .duration_since(std::time::UNIX_EPOCH)
-                    .map_or(0, |d| d.as_secs());
+                let now_secs = crate::clock::unix_seconds();
                 let threshold = now_secs.saturating_sub(duration.as_secs());
                 // History keys are the commit id big-endian, so lexicographic
                 // key order is commit order and the prunable rows are always a

src/txn/write/commit.rs

@@ -110,9 +110,7 @@ impl<V: Vfs + Clone> WriteTxn<'_, V> {
 
         // Commit-history entry (also materialized here). Its frees are never
         // reader-pinned, so they fold into the free-list like any other.
-        let unix_seconds = std::time::SystemTime::now()
-            .duration_since(std::time::UNIX_EPOCH)
-            .map_or(0, |d| d.as_secs());
+        let unix_seconds = crate::clock::unix_seconds();
         let history_meta = CommitHistoryMeta {
             active_root_page_id: new_root,
             catalog_root_page_id: new_catalog_root,

wasm-smoke/Cargo.toml

@@ -0,0 +1,19 @@
+# wasm32 smoke tests for pagedb.
+#
+# Separate crate on purpose: the pagedb dev-dependencies (tokio
+# rt-multi-thread, tempfile) do not compile for wasm32, and Cargo builds every
+# dev-dependency for a crate's test targets. This crate depends on pagedb with
+# the `opfs` feature only.
+[package]
+name = "pagedb-wasm-smoke"
+version = "0.0.0"
+edition = "2024"
+publish = false
+
+[lib]
+path = "src/lib.rs"
+
+[target.'cfg(all(target_arch = "wasm32", target_os = "unknown"))'.dependencies]
+wasm-bindgen-test = "0.3"
+tokio = { version = "1", features = ["rt", "macros", "sync", "io-util", "time"] }
+pagedb = { path = "..", features = ["opfs"] }

wasm-smoke/src/lib.rs

@@ -0,0 +1 @@
+//! wasm32 smoke-test crate; see tests/.