Initial IndexedDB Support (#33044)

Adds indexeddb support to servo. At the moment heed is being used as the
backend, although this can be swapped out by implementing `KvsEngine`.
This PR adds a thread + a thread pool for Indexeddb related operations.
Also `database_access_task_source` is added for Indexeddb related
operations.

This is a partial rewrite of #25214. (Reopened due to branching issue)

Fixes #6963

---------

Signed-off-by: Ashwin Naren <arihant2math@gmail.com>
Signed-off-by: Josh Matthews <josh@joshmatthews.net>
Co-authored-by: Rasmus Viitanen <rasviitanen@gmail.com>
Co-authored-by: Josh Matthews <josh@joshmatthews.net>

components/shared/net/indexeddb_thread.rs

@@ -0,0 +1,173 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use ipc_channel::ipc::IpcSender;
+use serde::{Deserialize, Serialize};
+use servo_url::origin::ImmutableOrigin;
+
+#[derive(Debug, Deserialize, Serialize)]
+pub enum IndexedDBThreadReturnType {
+    Open(Option<u64>),
+    NextSerialNumber(u64),
+    StartTransaction(Result<(), ()>),
+    Commit(Result<(), ()>),
+    Version(u64),
+    CreateObjectStore(Option<String>),
+    UpgradeVersion(Result<u64, ()>),
+    KVResult(Option<Vec<u8>>),
+    Exit,
+}
+
+// https://www.w3.org/TR/IndexedDB-2/#enumdef-idbtransactionmode
+#[derive(Debug, Deserialize, Serialize)]
+pub enum IndexedDBTxnMode {
+    Readonly,
+    Readwrite,
+    Versionchange,
+}
+
+// https://www.w3.org/TR/IndexedDB-2/#key-type
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub enum IndexedDBKeyType {
+    Number(Vec<u8>),
+    String(Vec<u8>),
+    Binary(Vec<u8>),
+    Date(Vec<u8>),
+    // FIXME:(arihant2math) implment Array(),
+}
+
+// https://www.w3.org/TR/IndexedDB-2/#key-range
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[allow(unused)]
+pub enum IndexedDBKeyRange {}
+
+// Operations that are not executed instantly, but rather added to a
+// queue that is eventually run.
+#[derive(Debug, Deserialize, Serialize)]
+pub enum AsyncOperation {
+    /// Gets the value associated with the given key in the associated idb data
+    GetItem(
+        IndexedDBKeyType, // Key
+    ),
+
+    /// Sets the value of the given key in the associated idb data
+    PutItem(
+        IndexedDBKeyType, // Key
+        Vec<u8>,          // Value
+        bool,             // Should overwrite
+    ),
+
+    /// Removes the key/value pair for the given key in the associated idb data
+    RemoveItem(
+        IndexedDBKeyType, // Key
+    ),
+
+    Count(
+        IndexedDBKeyType, // Key
+    ),
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+pub enum SyncOperation {
+    // Upgrades the version of the database
+    UpgradeVersion(
+        IpcSender<IndexedDBThreadReturnType>,
+        ImmutableOrigin,
+        String, // Database
+        u64,    // Serial number for the transaction
+        u64,    // Version to upgrade to
+    ),
+    // Checks if an object store has a key generator, used in e.g. Put
+    HasKeyGenerator(
+        IpcSender<bool>,
+        ImmutableOrigin,
+        String, // Database
+        String, // Store
+    ),
+
+    // Commits changes of a transaction to the database
+    Commit(
+        IpcSender<IndexedDBThreadReturnType>,
+        ImmutableOrigin,
+        String, // Database
+        u64,    // Transaction serial number
+    ),
+
+    // Creates a new store for the database
+    CreateObjectStore(
+        IpcSender<Result<(), ()>>,
+        ImmutableOrigin,
+        String, // Database
+        String, // Store
+        bool,
+    ),
+
+    DeleteObjectStore(
+        IpcSender<Result<(), ()>>,
+        ImmutableOrigin,
+        String, // Database
+        String, // Store
+    ),
+
+    CloseDatabase(
+        IpcSender<Result<(), ()>>,
+        ImmutableOrigin,
+        String, // Database
+    ),
+
+    OpenDatabase(
+        IpcSender<u64>, // Returns the version
+        ImmutableOrigin,
+        String,      // Database
+        Option<u64>, // Eventual version
+    ),
+
+    // Deletes the database
+    DeleteDatabase(
+        IpcSender<Result<(), ()>>,
+        ImmutableOrigin,
+        String, // Database
+    ),
+
+    // Returns an unique identifier that is used to be able to
+    // commit/abort transactions.
+    RegisterNewTxn(
+        IpcSender<u64>,
+        ImmutableOrigin,
+        String, // Database
+    ),
+
+    // Starts executing the requests of a transaction
+    // https://www.w3.org/TR/IndexedDB-2/#transaction-start
+    StartTransaction(
+        IpcSender<Result<(), ()>>,
+        ImmutableOrigin,
+        String, // Database
+        u64,    // The serial number of the mutating transaction
+    ),
+
+    // Returns the version of the database
+    Version(
+        IpcSender<u64>,
+        ImmutableOrigin,
+        String, // Database
+    ),
+
+    /// Send a reply when done cleaning up thread resources and then shut it down
+    Exit(IpcSender<IndexedDBThreadReturnType>),
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+pub enum IndexedDBThreadMsg {
+    Sync(SyncOperation),
+    Async(
+        IpcSender<Option<Vec<u8>>>, // Sender to send the result of the async operation
+        ImmutableOrigin,
+        String, // Database
+        String, // ObjectStore
+        u64,    // Serial number of the transaction that requests this operation
+        IndexedDBTxnMode,
+        AsyncOperation,
+    ),
+}