Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

4 files changed, 1255 insertions, 0 deletions

diff --git a/toolkit/components/kvstore/src/error.rs b/toolkit/components/kvstore/src/error.rs
new file mode 100644
index 0000000000..82ed2ce0d8
--- /dev/null
+++ b/toolkit/components/kvstore/src/error.rs
@@ -0,0 +1,89 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+use nserror::{
+    nsresult, NS_ERROR_FAILURE, NS_ERROR_NOT_IMPLEMENTED, NS_ERROR_NO_INTERFACE,
+    NS_ERROR_NULL_POINTER, NS_ERROR_UNEXPECTED,
+};
+use nsstring::nsCString;
+use rkv::{MigrateError, StoreError};
+use std::{io::Error as IoError, str::Utf8Error, string::FromUtf16Error, sync::PoisonError};
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum KeyValueError {
+    #[error("error converting string: {0:?}")]
+    ConvertBytes(#[from] Utf8Error),
+
+    #[error("error converting string: {0:?}")]
+    ConvertString(#[from] FromUtf16Error),
+
+    #[error("I/O error: {0:?}")]
+    IoError(#[from] IoError),
+
+    #[error("migrate error: {0:?}")]
+    MigrateError(#[from] MigrateError),
+
+    #[error("no interface '{0}'")]
+    NoInterface(&'static str),
+
+    // NB: We can avoid storing the nsCString error description
+    // once nsresult is a real type with a Display implementation
+    // per https://bugzilla.mozilla.org/show_bug.cgi?id=1513350.
+    #[error("error result {0}")]
+    Nsresult(nsCString, nsresult),
+
+    #[error("arg is null")]
+    NullPointer,
+
+    #[error("poison error getting read/write lock")]
+    PoisonError,
+
+    #[error("error reading key/value pair")]
+    Read,
+
+    #[error("store error: {0:?}")]
+    StoreError(#[from] StoreError),
+
+    #[error("unsupported owned value type")]
+    UnsupportedOwned,
+
+    #[error("unexpected value")]
+    UnexpectedValue,
+
+    #[error("unsupported variant type: {0}")]
+    UnsupportedVariant(u16),
+}
+
+impl From<nsresult> for KeyValueError {
+    fn from(result: nsresult) -> KeyValueError {
+        KeyValueError::Nsresult(result.error_name(), result)
+    }
+}
+
+impl From<KeyValueError> for nsresult {
+    fn from(err: KeyValueError) -> nsresult {
+        match err {
+            KeyValueError::ConvertBytes(_) => NS_ERROR_FAILURE,
+            KeyValueError::ConvertString(_) => NS_ERROR_FAILURE,
+            KeyValueError::IoError(_) => NS_ERROR_FAILURE,
+            KeyValueError::NoInterface(_) => NS_ERROR_NO_INTERFACE,
+            KeyValueError::Nsresult(_, result) => result,
+            KeyValueError::NullPointer => NS_ERROR_NULL_POINTER,
+            KeyValueError::PoisonError => NS_ERROR_UNEXPECTED,
+            KeyValueError::Read => NS_ERROR_FAILURE,
+            KeyValueError::StoreError(_) => NS_ERROR_FAILURE,
+            KeyValueError::MigrateError(_) => NS_ERROR_FAILURE,
+            KeyValueError::UnsupportedOwned => NS_ERROR_NOT_IMPLEMENTED,
+            KeyValueError::UnexpectedValue => NS_ERROR_UNEXPECTED,
+            KeyValueError::UnsupportedVariant(_) => NS_ERROR_NOT_IMPLEMENTED,
+        }
+    }
+}
+
+impl<T> From<PoisonError<T>> for KeyValueError {
+    fn from(_err: PoisonError<T>) -> KeyValueError {
+        KeyValueError::PoisonError
+    }
+}
diff --git a/toolkit/components/kvstore/src/lib.rs b/toolkit/components/kvstore/src/lib.rs
new file mode 100644
index 0000000000..5601ecb12a
--- /dev/null
+++ b/toolkit/components/kvstore/src/lib.rs
@@ -0,0 +1,367 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+extern crate atomic_refcell;
+extern crate crossbeam_utils;
+#[macro_use]
+extern crate cstr;
+extern crate libc;
+extern crate log;
+extern crate moz_task;
+extern crate nserror;
+extern crate nsstring;
+extern crate rkv;
+extern crate storage_variant;
+extern crate tempfile;
+extern crate thin_vec;
+extern crate thiserror;
+extern crate xpcom;
+
+mod error;
+mod owned_value;
+mod task;
+
+use atomic_refcell::AtomicRefCell;
+use error::KeyValueError;
+use libc::c_void;
+use moz_task::{create_background_task_queue, DispatchOptions, TaskRunnable};
+use nserror::{nsresult, NS_ERROR_FAILURE, NS_OK};
+use nsstring::{nsACString, nsCString};
+use owned_value::{owned_to_variant, variant_to_owned};
+use rkv::backend::{SafeModeDatabase, SafeModeEnvironment};
+use rkv::OwnedValue;
+use std::{
+    ptr,
+    sync::{Arc, RwLock},
+    vec::IntoIter,
+};
+use task::{
+    ClearTask, DeleteTask, EnumerateTask, GetOrCreateTask, GetTask, HasTask, PutTask, WriteManyTask,
+};
+use thin_vec::ThinVec;
+use xpcom::{
+    getter_addrefs,
+    interfaces::{
+        nsIKeyValueDatabaseCallback, nsIKeyValueEnumeratorCallback, nsIKeyValuePair,
+        nsIKeyValueVariantCallback, nsIKeyValueVoidCallback, nsISerialEventTarget, nsIVariant,
+    },
+    nsIID, xpcom, xpcom_method, RefPtr,
+};
+
+type Rkv = rkv::Rkv<SafeModeEnvironment>;
+type SingleStore = rkv::SingleStore<SafeModeDatabase>;
+type KeyValuePairResult = Result<(String, OwnedValue), KeyValueError>;
+
+#[no_mangle]
+pub unsafe extern "C" fn nsKeyValueServiceConstructor(
+    iid: &nsIID,
+    result: *mut *mut c_void,
+) -> nsresult {
+    *result = ptr::null_mut();
+
+    let service = KeyValueService::new();
+    service.QueryInterface(iid, result)
+}
+
+// For each public XPCOM method in the nsIKeyValue* interfaces, we implement
+// a pair of Rust methods:
+//
+//   1. a method named after the XPCOM (as modified by the XPIDL parser, i.e.
+//      by capitalization of its initial letter) that returns an nsresult;
+//
+//   2. a method with a Rust-y name that returns a Result<(), KeyValueError>.
+//
+// XPCOM calls the first method, which is only responsible for calling
+// the second one and converting its Result to an nsresult (logging errors
+// in the process).  The second method is responsible for doing the work.
+//
+// For example, given an XPCOM method FooBar, we implement a method FooBar
+// that calls a method foo_bar.  foo_bar returns a Result<(), KeyValueError>,
+// and FooBar converts that to an nsresult.
+//
+// This design allows us to use Rust idioms like the question mark operator
+// to simplify the implementation in the second method while returning XPCOM-
+// compatible nsresult values to XPCOM callers.
+//
+// The XPCOM methods are implemented using the xpcom_method! declarative macro
+// from the xpcom crate.
+
+#[xpcom(implement(nsIKeyValueService), atomic)]
+pub struct KeyValueService {}
+
+impl KeyValueService {
+    fn new() -> RefPtr<KeyValueService> {
+        KeyValueService::allocate(InitKeyValueService {})
+    }
+
+    xpcom_method!(
+        get_or_create => GetOrCreate(
+            callback: *const nsIKeyValueDatabaseCallback,
+            path: *const nsACString,
+            name: *const nsACString
+        )
+    );
+
+    fn get_or_create(
+        &self,
+        callback: &nsIKeyValueDatabaseCallback,
+        path: &nsACString,
+        name: &nsACString,
+    ) -> Result<(), nsresult> {
+        let task = Box::new(GetOrCreateTask::new(
+            RefPtr::new(callback),
+            nsCString::from(path),
+            nsCString::from(name),
+        ));
+
+        TaskRunnable::new("KVService::GetOrCreate", task)?
+            .dispatch_background_task_with_options(DispatchOptions::default().may_block(true))
+    }
+}
+
+#[xpcom(implement(nsIKeyValueDatabase), atomic)]
+pub struct KeyValueDatabase {
+    rkv: Arc<RwLock<Rkv>>,
+    store: SingleStore,
+    queue: RefPtr<nsISerialEventTarget>,
+}
+
+impl KeyValueDatabase {
+    fn new(
+        rkv: Arc<RwLock<Rkv>>,
+        store: SingleStore,
+    ) -> Result<RefPtr<KeyValueDatabase>, KeyValueError> {
+        let queue = create_background_task_queue(cstr!("KeyValueDatabase"))?;
+        Ok(KeyValueDatabase::allocate(InitKeyValueDatabase {
+            rkv,
+            store,
+            queue,
+        }))
+    }
+
+    xpcom_method!(
+        put => Put(
+            callback: *const nsIKeyValueVoidCallback,
+            key: *const nsACString,
+            value: *const nsIVariant
+        )
+    );
+
+    fn put(
+        &self,
+        callback: &nsIKeyValueVoidCallback,
+        key: &nsACString,
+        value: &nsIVariant,
+    ) -> Result<(), nsresult> {
+        let value = variant_to_owned(value)?.ok_or(KeyValueError::UnexpectedValue)?;
+
+        let task = Box::new(PutTask::new(
+            RefPtr::new(callback),
+            Arc::clone(&self.rkv),
+            self.store,
+            nsCString::from(key),
+            value,
+        ));
+
+        TaskRunnable::dispatch(TaskRunnable::new("KVDatabase::Put", task)?, &self.queue)
+    }
+
+    xpcom_method!(
+        write_many => WriteMany(
+            callback: *const nsIKeyValueVoidCallback,
+            pairs: *const ThinVec<Option<RefPtr<nsIKeyValuePair>>>
+        )
+    );
+
+    fn write_many(
+        &self,
+        callback: &nsIKeyValueVoidCallback,
+        pairs: &ThinVec<Option<RefPtr<nsIKeyValuePair>>>,
+    ) -> Result<(), nsresult> {
+        let mut entries = Vec::with_capacity(pairs.len());
+
+        for pair in pairs {
+            let pair = pair
+                .as_ref()
+                .ok_or(nsresult::from(KeyValueError::UnexpectedValue))?;
+
+            let mut key = nsCString::new();
+            unsafe { pair.GetKey(&mut *key) }.to_result()?;
+            if key.is_empty() {
+                return Err(nsresult::from(KeyValueError::UnexpectedValue));
+            }
+
+            let val: RefPtr<nsIVariant> = getter_addrefs(|p| unsafe { pair.GetValue(p) })?;
+            let value = variant_to_owned(&val)?;
+            entries.push((key, value));
+        }
+
+        let task = Box::new(WriteManyTask::new(
+            RefPtr::new(callback),
+            Arc::clone(&self.rkv),
+            self.store,
+            entries,
+        ));
+
+        TaskRunnable::dispatch(
+            TaskRunnable::new("KVDatabase::WriteMany", task)?,
+            &self.queue,
+        )
+    }
+
+    xpcom_method!(
+        get => Get(
+            callback: *const nsIKeyValueVariantCallback,
+            key: *const nsACString,
+            default_value: *const nsIVariant
+        )
+    );
+
+    fn get(
+        &self,
+        callback: &nsIKeyValueVariantCallback,
+        key: &nsACString,
+        default_value: &nsIVariant,
+    ) -> Result<(), nsresult> {
+        let task = Box::new(GetTask::new(
+            RefPtr::new(callback),
+            Arc::clone(&self.rkv),
+            self.store,
+            nsCString::from(key),
+            variant_to_owned(default_value)?,
+        ));
+
+        TaskRunnable::dispatch(TaskRunnable::new("KVDatabase::Get", task)?, &self.queue)
+    }
+
+    xpcom_method!(
+        has => Has(callback: *const nsIKeyValueVariantCallback, key: *const nsACString)
+    );
+
+    fn has(&self, callback: &nsIKeyValueVariantCallback, key: &nsACString) -> Result<(), nsresult> {
+        let task = Box::new(HasTask::new(
+            RefPtr::new(callback),
+            Arc::clone(&self.rkv),
+            self.store,
+            nsCString::from(key),
+        ));
+
+        TaskRunnable::dispatch(TaskRunnable::new("KVDatabase::Has", task)?, &self.queue)
+    }
+
+    xpcom_method!(
+        delete => Delete(callback: *const nsIKeyValueVoidCallback, key: *const nsACString)
+    );
+
+    fn delete(&self, callback: &nsIKeyValueVoidCallback, key: &nsACString) -> Result<(), nsresult> {
+        let task = Box::new(DeleteTask::new(
+            RefPtr::new(callback),
+            Arc::clone(&self.rkv),
+            self.store,
+            nsCString::from(key),
+        ));
+
+        TaskRunnable::dispatch(TaskRunnable::new("KVDatabase::Delete", task)?, &self.queue)
+    }
+
+    xpcom_method!(
+        clear => Clear(callback: *const nsIKeyValueVoidCallback)
+    );
+
+    fn clear(&self, callback: &nsIKeyValueVoidCallback) -> Result<(), nsresult> {
+        let task = Box::new(ClearTask::new(
+            RefPtr::new(callback),
+            Arc::clone(&self.rkv),
+            self.store,
+        ));
+
+        TaskRunnable::dispatch(TaskRunnable::new("KVDatabase::Clear", task)?, &self.queue)
+    }
+
+    xpcom_method!(
+        enumerate => Enumerate(
+            callback: *const nsIKeyValueEnumeratorCallback,
+            from_key: *const nsACString,
+            to_key: *const nsACString
+        )
+    );
+
+    fn enumerate(
+        &self,
+        callback: &nsIKeyValueEnumeratorCallback,
+        from_key: &nsACString,
+        to_key: &nsACString,
+    ) -> Result<(), nsresult> {
+        let task = Box::new(EnumerateTask::new(
+            RefPtr::new(callback),
+            Arc::clone(&self.rkv),
+            self.store,
+            nsCString::from(from_key),
+            nsCString::from(to_key),
+        ));
+
+        TaskRunnable::dispatch(
+            TaskRunnable::new("KVDatabase::Enumerate", task)?,
+            &self.queue,
+        )
+    }
+}
+
+#[xpcom(implement(nsIKeyValueEnumerator), atomic)]
+pub struct KeyValueEnumerator {
+    iter: AtomicRefCell<IntoIter<KeyValuePairResult>>,
+}
+
+impl KeyValueEnumerator {
+    fn new(pairs: Vec<KeyValuePairResult>) -> RefPtr<KeyValueEnumerator> {
+        KeyValueEnumerator::allocate(InitKeyValueEnumerator {
+            iter: AtomicRefCell::new(pairs.into_iter()),
+        })
+    }
+
+    xpcom_method!(has_more_elements => HasMoreElements() -> bool);
+
+    fn has_more_elements(&self) -> Result<bool, KeyValueError> {
+        Ok(!self.iter.borrow().as_slice().is_empty())
+    }
+
+    xpcom_method!(get_next => GetNext() -> *const nsIKeyValuePair);
+
+    fn get_next(&self) -> Result<RefPtr<nsIKeyValuePair>, KeyValueError> {
+        let mut iter = self.iter.borrow_mut();
+        let (key, value) = iter
+            .next()
+            .ok_or_else(|| KeyValueError::from(NS_ERROR_FAILURE))??;
+
+        // We fail on retrieval of the key/value pair if the key isn't valid
+        // UTF-*, if the value is unexpected, or if we encountered a store error
+        // while retrieving the pair.
+        Ok(RefPtr::new(
+            KeyValuePair::new(key, value).coerce::<nsIKeyValuePair>(),
+        ))
+    }
+}
+
+#[xpcom(implement(nsIKeyValuePair), atomic)]
+pub struct KeyValuePair {
+    key: String,
+    value: OwnedValue,
+}
+
+impl KeyValuePair {
+    fn new(key: String, value: OwnedValue) -> RefPtr<KeyValuePair> {
+        KeyValuePair::allocate(InitKeyValuePair { key, value })
+    }
+
+    xpcom_method!(get_key => GetKey() -> nsACString);
+    xpcom_method!(get_value => GetValue() -> *const nsIVariant);
+
+    fn get_key(&self) -> Result<nsCString, KeyValueError> {
+        Ok(nsCString::from(&self.key))
+    }
+
+    fn get_value(&self) -> Result<RefPtr<nsIVariant>, KeyValueError> {
+        Ok(owned_to_variant(self.value.clone())?)
+    }
+}
diff --git a/toolkit/components/kvstore/src/owned_value.rs b/toolkit/components/kvstore/src/owned_value.rs
new file mode 100644
index 0000000000..a22abcb8da
--- /dev/null
+++ b/toolkit/components/kvstore/src/owned_value.rs
@@ -0,0 +1,72 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+use error::KeyValueError;
+use nsstring::{nsCString, nsString};
+use rkv::OwnedValue;
+use std::convert::TryInto;
+use storage_variant::{DataType, NsIVariantExt, VariantType};
+use xpcom::{interfaces::nsIVariant, RefPtr};
+
+pub fn owned_to_variant(owned: OwnedValue) -> Result<RefPtr<nsIVariant>, KeyValueError> {
+    match owned {
+        OwnedValue::Bool(val) => Ok(val.into_variant()),
+        OwnedValue::I64(val) => Ok(val.into_variant()),
+        OwnedValue::F64(val) => Ok(val.into_variant()),
+        OwnedValue::Str(ref val) => Ok(nsString::from(val).into_variant()),
+
+        // kvstore doesn't (yet?) support these types of OwnedValue,
+        // and we should never encounter them, but we need to exhaust
+        // all possible variants of the OwnedValue enum.
+        OwnedValue::Instant(_) => Err(KeyValueError::UnsupportedOwned),
+        OwnedValue::Json(_) => Err(KeyValueError::UnsupportedOwned),
+        OwnedValue::U64(_) => Err(KeyValueError::UnsupportedOwned),
+        OwnedValue::Uuid(_) => Err(KeyValueError::UnsupportedOwned),
+        OwnedValue::Blob(_) => Err(KeyValueError::UnsupportedOwned),
+    }
+}
+
+pub fn variant_to_owned(variant: &nsIVariant) -> Result<Option<OwnedValue>, KeyValueError> {
+    let data_type = variant.get_data_type();
+
+    match data_type.try_into() {
+        Ok(DataType::Int32) => {
+            let mut val: i32 = 0;
+            unsafe { variant.GetAsInt32(&mut val) }.to_result()?;
+            Ok(Some(OwnedValue::I64(val.into())))
+        }
+        Ok(DataType::Int64) => {
+            let mut val: i64 = 0;
+            unsafe { variant.GetAsInt64(&mut val) }.to_result()?;
+            Ok(Some(OwnedValue::I64(val)))
+        }
+        Ok(DataType::Double) => {
+            let mut val: f64 = 0.0;
+            unsafe { variant.GetAsDouble(&mut val) }.to_result()?;
+            Ok(Some(OwnedValue::F64(val)))
+        }
+        Ok(DataType::CString)
+        | Ok(DataType::CharStr)
+        | Ok(DataType::StringSizeIs)
+        | Ok(DataType::Utf8String) => {
+            let mut val: nsCString = nsCString::new();
+            unsafe { variant.GetAsAUTF8String(&mut *val) }.to_result()?;
+            let s = std::str::from_utf8(&*val)?;
+            Ok(Some(OwnedValue::Str(s.into())))
+        }
+        Ok(DataType::AString) | Ok(DataType::WCharStr) | Ok(DataType::WStringSizeIs) => {
+            let mut val: nsString = nsString::new();
+            unsafe { variant.GetAsAString(&mut *val) }.to_result()?;
+            let str = String::from_utf16(&val)?;
+            Ok(Some(OwnedValue::Str(str)))
+        }
+        Ok(DataType::Bool) => {
+            let mut val: bool = false;
+            unsafe { variant.GetAsBool(&mut val) }.to_result()?;
+            Ok(Some(OwnedValue::Bool(val)))
+        }
+        Ok(DataType::Void) | Ok(DataType::EmptyArray) | Ok(DataType::Empty) => Ok(None),
+        Err(_) => Err(KeyValueError::UnsupportedVariant(data_type)),
+    }
+}
diff --git a/toolkit/components/kvstore/src/task.rs b/toolkit/components/kvstore/src/task.rs
new file mode 100644
index 0000000000..3608dc9665
--- /dev/null
+++ b/toolkit/components/kvstore/src/task.rs
@@ -0,0 +1,727 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+extern crate xpcom;
+
+use crossbeam_utils::atomic::AtomicCell;
+use error::KeyValueError;
+use moz_task::Task;
+use nserror::{nsresult, NS_ERROR_FAILURE};
+use nsstring::nsCString;
+use owned_value::owned_to_variant;
+use rkv::backend::{BackendInfo, SafeMode, SafeModeDatabase, SafeModeEnvironment};
+use rkv::{OwnedValue, StoreError, StoreOptions, Value};
+use std::{
+    path::Path,
+    str,
+    sync::{Arc, RwLock},
+};
+use storage_variant::VariantType;
+use xpcom::{
+    interfaces::{
+        nsIKeyValueDatabaseCallback, nsIKeyValueEnumeratorCallback, nsIKeyValueVariantCallback,
+        nsIKeyValueVoidCallback, nsIVariant,
+    },
+    RefPtr, ThreadBoundRefPtr,
+};
+use KeyValueDatabase;
+use KeyValueEnumerator;
+use KeyValuePairResult;
+
+type Manager = rkv::Manager<SafeModeEnvironment>;
+type Rkv = rkv::Rkv<SafeModeEnvironment>;
+type SingleStore = rkv::SingleStore<SafeModeDatabase>;
+
+/// A macro to generate a done() implementation for a Task.
+/// Takes one argument that specifies the type of the Task's callback function:
+///   value: a callback function that takes a value
+///   void: the callback function doesn't take a value
+///
+/// The "value" variant calls self.convert() to convert a successful result
+/// into the value to pass to the callback function.  So if you generate done()
+/// for a callback that takes a value, ensure you also implement convert()!
+macro_rules! task_done {
+    (value) => {
+        fn done(&self) -> Result<(), nsresult> {
+            // If TaskRunnable calls Task.done() to return a result on the
+            // main thread before TaskRunnable returns on the database thread,
+            // then the Task will get dropped on the database thread.
+            //
+            // But the callback is an nsXPCWrappedJS that isn't safe to release
+            // on the database thread.  So we move it out of the Task here to ensure
+            // it gets released on the main thread.
+            let threadbound = self.callback.swap(None).ok_or(NS_ERROR_FAILURE)?;
+            let callback = threadbound.get_ref().ok_or(NS_ERROR_FAILURE)?;
+
+            match self.result.swap(None) {
+                Some(Ok(value)) => unsafe { callback.Resolve(self.convert(value)?.coerce()) },
+                Some(Err(err)) => unsafe { callback.Reject(&*nsCString::from(err.to_string())) },
+                None => unsafe { callback.Reject(&*nsCString::from("unexpected")) },
+            }
+            .to_result()
+        }
+    };
+
+    (void) => {
+        fn done(&self) -> Result<(), nsresult> {
+            // If TaskRunnable calls Task.done() to return a result on the
+            // main thread before TaskRunnable returns on the database thread,
+            // then the Task will get dropped on the database thread.
+            //
+            // But the callback is an nsXPCWrappedJS that isn't safe to release
+            // on the database thread.  So we move it out of the Task here to ensure
+            // it gets released on the main thread.
+            let threadbound = self.callback.swap(None).ok_or(NS_ERROR_FAILURE)?;
+            let callback = threadbound.get_ref().ok_or(NS_ERROR_FAILURE)?;
+
+            match self.result.swap(None) {
+                Some(Ok(())) => unsafe { callback.Resolve() },
+                Some(Err(err)) => unsafe { callback.Reject(&*nsCString::from(err.to_string())) },
+                None => unsafe { callback.Reject(&*nsCString::from("unexpected")) },
+            }
+            .to_result()
+        }
+    };
+}
+
+/// A tuple comprising an Arc<RwLock<Rkv>> and a SingleStore, which is
+/// the result of GetOrCreateTask.  We declare this type because otherwise
+/// Clippy complains "error: very complex type used. Consider factoring
+/// parts into `type` definitions" (i.e. clippy::type-complexity) when we
+/// declare the type of `GetOrCreateTask::result`.
+type RkvStoreTuple = (Arc<RwLock<Rkv>>, SingleStore);
+
+// The threshold for active resizing.
+const RESIZE_RATIO: f32 = 0.85;
+
+/// The threshold (50 MB) to switch the resizing policy from the double size to
+/// the constant increment for active resizing.
+const INCREMENTAL_RESIZE_THRESHOLD: usize = 52_428_800;
+
+/// The incremental resize step (5 MB)
+const INCREMENTAL_RESIZE_STEP: usize = 5_242_880;
+
+/// The RKV disk page size and mask.
+const PAGE_SIZE: usize = 4096;
+const PAGE_SIZE_MASK: usize = 0b_1111_1111_1111;
+
+/// Round the non-zero size to the multiple of page size greater or equal.
+///
+/// It does not handle the special cases such as size zero and overflow,
+/// because even if that happens (extremely unlikely though), RKV will
+/// ignore the new size if it's smaller than the current size.
+///
+/// E.g:
+///     [   1 -  4096] -> 4096,
+///     [4097 -  8192] -> 8192,
+///     [8193 - 12286] -> 12286,
+fn round_to_pagesize(size: usize) -> usize {
+    if size & PAGE_SIZE_MASK == 0 {
+        size
+    } else {
+        (size & !PAGE_SIZE_MASK) + PAGE_SIZE
+    }
+}
+
+/// Kvstore employes two auto resizing strategies: active and passive resizing.
+/// They work together to liberate consumers from having to guess the "proper"
+/// size of the store upfront. See more detail about this in Bug 1543861.
+///
+/// Active resizing that is performed at the store startup.
+///
+/// It either increases the size in double, or by a constant size if its size
+/// reaches INCREMENTAL_RESIZE_THRESHOLD.
+///
+/// Note that on Linux / MAC OSX, the increased size would only take effect if
+/// there is a write transaction committed afterwards.
+fn active_resize(env: &Rkv) -> Result<(), StoreError> {
+    let info = env.info()?;
+    let current_size = info.map_size();
+
+    let size = if current_size < INCREMENTAL_RESIZE_THRESHOLD {
+        current_size << 1
+    } else {
+        current_size + INCREMENTAL_RESIZE_STEP
+    };
+
+    env.set_map_size(size)?;
+    Ok(())
+}
+
+/// Passive resizing that is performed when the MAP_FULL error occurs. It
+/// increases the store with a `wanted` size.
+///
+/// Note that the `wanted` size must be rounded to a multiple of page size
+/// by using `round_to_pagesize`.
+fn passive_resize(env: &Rkv, wanted: usize) -> Result<(), StoreError> {
+    let info = env.info()?;
+    let current_size = info.map_size();
+    env.set_map_size(current_size + wanted)?;
+    Ok(())
+}
+
+pub struct GetOrCreateTask {
+    callback: AtomicCell<Option<ThreadBoundRefPtr<nsIKeyValueDatabaseCallback>>>,
+    path: nsCString,
+    name: nsCString,
+    result: AtomicCell<Option<Result<RkvStoreTuple, KeyValueError>>>,
+}
+
+impl GetOrCreateTask {
+    pub fn new(
+        callback: RefPtr<nsIKeyValueDatabaseCallback>,
+        path: nsCString,
+        name: nsCString,
+    ) -> GetOrCreateTask {
+        GetOrCreateTask {
+            callback: AtomicCell::new(Some(ThreadBoundRefPtr::new(callback))),
+            path,
+            name,
+            result: AtomicCell::default(),
+        }
+    }
+
+    fn convert(&self, result: RkvStoreTuple) -> Result<RefPtr<KeyValueDatabase>, KeyValueError> {
+        Ok(KeyValueDatabase::new(result.0, result.1)?)
+    }
+}
+
+impl Task for GetOrCreateTask {
+    fn run(&self) {
+        // We do the work within a closure that returns a Result so we can
+        // use the ? operator to simplify the implementation.
+        self.result
+            .store(Some(|| -> Result<RkvStoreTuple, KeyValueError> {
+                let store;
+                let mut manager = Manager::singleton().write()?;
+                // Note that path canonicalization is diabled to work around crashes on Fennec:
+                // https://bugzilla.mozilla.org/show_bug.cgi?id=1531887
+                let path = Path::new(str::from_utf8(&self.path)?);
+                let rkv = manager.get_or_create(path, Rkv::new::<SafeMode>)?;
+                {
+                    let env = rkv.read()?;
+                    let load_ratio = env.load_ratio()?.unwrap_or(0.0);
+                    if load_ratio > RESIZE_RATIO {
+                        active_resize(&env)?;
+                    }
+                    store = env.open_single(str::from_utf8(&self.name)?, StoreOptions::create())?;
+                }
+                Ok((rkv, store))
+            }()));
+    }
+
+    task_done!(value);
+}
+
+pub struct PutTask {
+    callback: AtomicCell<Option<ThreadBoundRefPtr<nsIKeyValueVoidCallback>>>,
+    rkv: Arc<RwLock<Rkv>>,
+    store: SingleStore,
+    key: nsCString,
+    value: OwnedValue,
+    result: AtomicCell<Option<Result<(), KeyValueError>>>,
+}
+
+impl PutTask {
+    pub fn new(
+        callback: RefPtr<nsIKeyValueVoidCallback>,
+        rkv: Arc<RwLock<Rkv>>,
+        store: SingleStore,
+        key: nsCString,
+        value: OwnedValue,
+    ) -> PutTask {
+        PutTask {
+            callback: AtomicCell::new(Some(ThreadBoundRefPtr::new(callback))),
+            rkv,
+            store,
+            key,
+            value,
+            result: AtomicCell::default(),
+        }
+    }
+}
+
+impl Task for PutTask {
+    fn run(&self) {
+        // We do the work within a closure that returns a Result so we can
+        // use the ? operator to simplify the implementation.
+        self.result.store(Some(|| -> Result<(), KeyValueError> {
+            let env = self.rkv.read()?;
+            let key = str::from_utf8(&self.key)?;
+            let v = Value::from(&self.value);
+            let mut resized = false;
+
+            // Use a loop here in case we want to retry from a recoverable
+            // error such as `StoreError::MapFull`.
+            loop {
+                let mut writer = env.write()?;
+
+                match self.store.put(&mut writer, key, &v) {
+                    Ok(_) => (),
+
+                    // Only handle the first MapFull error via passive resizing.
+                    // Propogate the subsequent MapFull error.
+                    Err(StoreError::MapFull) if !resized => {
+                        // abort the failed transaction for resizing.
+                        writer.abort();
+
+                        // calculate the size of pairs and resize the store accordingly.
+                        let pair_size =
+                            key.len() + v.serialized_size().map_err(StoreError::from)? as usize;
+                        let wanted = round_to_pagesize(pair_size);
+                        passive_resize(&env, wanted)?;
+                        resized = true;
+                        continue;
+                    }
+
+                    Err(err) => return Err(KeyValueError::StoreError(err)),
+                }
+
+                // Ignore errors caused by simultaneous access.
+                // We intend to investigate/revert this in bug 1810212.
+                match writer.commit() {
+                    Err(StoreError::IoError(e)) if e.kind() == std::io::ErrorKind::NotFound => {
+                        // Explicitly ignore errors from simultaneous access.
+                    }
+                    Err(e) => return Err(From::from(e)),
+                    _ => (),
+                };
+                break;
+            }
+
+            Ok(())
+        }()));
+    }
+
+    task_done!(void);
+}
+
+pub struct WriteManyTask {
+    callback: AtomicCell<Option<ThreadBoundRefPtr<nsIKeyValueVoidCallback>>>,
+    rkv: Arc<RwLock<Rkv>>,
+    store: SingleStore,
+    pairs: Vec<(nsCString, Option<OwnedValue>)>,
+    result: AtomicCell<Option<Result<(), KeyValueError>>>,
+}
+
+impl WriteManyTask {
+    pub fn new(
+        callback: RefPtr<nsIKeyValueVoidCallback>,
+        rkv: Arc<RwLock<Rkv>>,
+        store: SingleStore,
+        pairs: Vec<(nsCString, Option<OwnedValue>)>,
+    ) -> WriteManyTask {
+        WriteManyTask {
+            callback: AtomicCell::new(Some(ThreadBoundRefPtr::new(callback))),
+            rkv,
+            store,
+            pairs,
+            result: AtomicCell::default(),
+        }
+    }
+
+    fn calc_pair_size(&self) -> Result<usize, StoreError> {
+        let mut total = 0;
+
+        for (key, value) in self.pairs.iter() {
+            if let Some(val) = value {
+                total += key.len();
+                total += Value::from(val)
+                    .serialized_size()
+                    .map_err(StoreError::from)? as usize;
+            }
+        }
+
+        Ok(total)
+    }
+}
+
+impl Task for WriteManyTask {
+    fn run(&self) {
+        // We do the work within a closure that returns a Result so we can
+        // use the ? operator to simplify the implementation.
+        self.result.store(Some(|| -> Result<(), KeyValueError> {
+            let env = self.rkv.read()?;
+            let mut resized = false;
+
+            // Use a loop here in case we want to retry from a recoverable
+            // error such as `StoreError::MapFull`.
+            'outer: loop {
+                let mut writer = env.write()?;
+
+                for (key, value) in self.pairs.iter() {
+                    let key = str::from_utf8(key)?;
+                    match value {
+                        // To put.
+                        Some(val) => {
+                            match self.store.put(&mut writer, key, &Value::from(val)) {
+                                Ok(_) => (),
+
+                                // Only handle the first MapFull error via passive resizing.
+                                // Propogate the subsequent MapFull error.
+                                Err(StoreError::MapFull) if !resized => {
+                                    // Abort the failed transaction for resizing.
+                                    writer.abort();
+
+                                    // Calculate the size of pairs and resize accordingly.
+                                    let pair_size = self.calc_pair_size()?;
+                                    let wanted = round_to_pagesize(pair_size);
+                                    passive_resize(&env, wanted)?;
+                                    resized = true;
+                                    continue 'outer;
+                                }
+
+                                Err(err) => return Err(KeyValueError::StoreError(err)),
+                            }
+                        }
+                        // To delete.
+                        None => {
+                            match self.store.delete(&mut writer, key) {
+                                Ok(_) => (),
+
+                                // RKV fails with an error if the key to delete wasn't found,
+                                // and Rkv returns that error, but we ignore it, as we expect most
+                                // of our consumers to want this behavior.
+                                Err(StoreError::KeyValuePairNotFound) => (),
+
+                                Err(err) => return Err(KeyValueError::StoreError(err)),
+                            };
+                        }
+                    }
+                }
+
+                // Ignore errors caused by simultaneous access.
+                // We intend to investigate/revert this in bug 1810212.
+                match writer.commit() {
+                    Err(StoreError::IoError(e)) if e.kind() == std::io::ErrorKind::NotFound => {
+                        // Explicitly ignore errors from simultaneous access.
+                    }
+                    Err(e) => return Err(From::from(e)),
+                    _ => (),
+                };
+                break; // 'outer: loop
+            }
+
+            Ok(())
+        }()));
+    }
+
+    task_done!(void);
+}
+
+pub struct GetTask {
+    callback: AtomicCell<Option<ThreadBoundRefPtr<nsIKeyValueVariantCallback>>>,
+    rkv: Arc<RwLock<Rkv>>,
+    store: SingleStore,
+    key: nsCString,
+    default_value: Option<OwnedValue>,
+    result: AtomicCell<Option<Result<Option<OwnedValue>, KeyValueError>>>,
+}
+
+impl GetTask {
+    pub fn new(
+        callback: RefPtr<nsIKeyValueVariantCallback>,
+        rkv: Arc<RwLock<Rkv>>,
+        store: SingleStore,
+        key: nsCString,
+        default_value: Option<OwnedValue>,
+    ) -> GetTask {
+        GetTask {
+            callback: AtomicCell::new(Some(ThreadBoundRefPtr::new(callback))),
+            rkv,
+            store,
+            key,
+            default_value,
+            result: AtomicCell::default(),
+        }
+    }
+
+    fn convert(&self, result: Option<OwnedValue>) -> Result<RefPtr<nsIVariant>, KeyValueError> {
+        Ok(match result {
+            Some(val) => owned_to_variant(val)?,
+            None => ().into_variant(),
+        })
+    }
+}
+
+impl Task for GetTask {
+    fn run(&self) {
+        // We do the work within a closure that returns a Result so we can
+        // use the ? operator to simplify the implementation.
+        self.result
+            .store(Some(|| -> Result<Option<OwnedValue>, KeyValueError> {
+                let key = str::from_utf8(&self.key)?;
+                let env = self.rkv.read()?;
+                let reader = env.read()?;
+                let value = self.store.get(&reader, key)?;
+
+                Ok(match value {
+                    Some(value) => Some(OwnedValue::from(&value)),
+                    None => match self.default_value {
+                        Some(ref val) => Some(val.clone()),
+                        None => None,
+                    },
+                })
+            }()));
+    }
+
+    task_done!(value);
+}
+
+pub struct HasTask {
+    callback: AtomicCell<Option<ThreadBoundRefPtr<nsIKeyValueVariantCallback>>>,
+    rkv: Arc<RwLock<Rkv>>,
+    store: SingleStore,
+    key: nsCString,
+    result: AtomicCell<Option<Result<bool, KeyValueError>>>,
+}
+
+impl HasTask {
+    pub fn new(
+        callback: RefPtr<nsIKeyValueVariantCallback>,
+        rkv: Arc<RwLock<Rkv>>,
+        store: SingleStore,
+        key: nsCString,
+    ) -> HasTask {
+        HasTask {
+            callback: AtomicCell::new(Some(ThreadBoundRefPtr::new(callback))),
+            rkv,
+            store,
+            key,
+            result: AtomicCell::default(),
+        }
+    }
+
+    fn convert(&self, result: bool) -> Result<RefPtr<nsIVariant>, KeyValueError> {
+        Ok(result.into_variant())
+    }
+}
+
+impl Task for HasTask {
+    fn run(&self) {
+        // We do the work within a closure that returns a Result so we can
+        // use the ? operator to simplify the implementation.
+        self.result.store(Some(|| -> Result<bool, KeyValueError> {
+            let key = str::from_utf8(&self.key)?;
+            let env = self.rkv.read()?;
+            let reader = env.read()?;
+            let value = self.store.get(&reader, key)?;
+            Ok(value.is_some())
+        }()));
+    }
+
+    task_done!(value);
+}
+
+pub struct DeleteTask {
+    callback: AtomicCell<Option<ThreadBoundRefPtr<nsIKeyValueVoidCallback>>>,
+    rkv: Arc<RwLock<Rkv>>,
+    store: SingleStore,
+    key: nsCString,
+    result: AtomicCell<Option<Result<(), KeyValueError>>>,
+}
+
+impl DeleteTask {
+    pub fn new(
+        callback: RefPtr<nsIKeyValueVoidCallback>,
+        rkv: Arc<RwLock<Rkv>>,
+        store: SingleStore,
+        key: nsCString,
+    ) -> DeleteTask {
+        DeleteTask {
+            callback: AtomicCell::new(Some(ThreadBoundRefPtr::new(callback))),
+            rkv,
+            store,
+            key,
+            result: AtomicCell::default(),
+        }
+    }
+}
+
+impl Task for DeleteTask {
+    fn run(&self) {
+        // We do the work within a closure that returns a Result so we can
+        // use the ? operator to simplify the implementation.
+        self.result.store(Some(|| -> Result<(), KeyValueError> {
+            let key = str::from_utf8(&self.key)?;
+            let env = self.rkv.read()?;
+            let mut writer = env.write()?;
+
+            match self.store.delete(&mut writer, key) {
+                Ok(_) => (),
+
+                // RKV fails with an error if the key to delete wasn't found,
+                // and Rkv returns that error, but we ignore it, as we expect most
+                // of our consumers to want this behavior.
+                Err(StoreError::KeyValuePairNotFound) => (),
+
+                Err(err) => return Err(KeyValueError::StoreError(err)),
+            };
+
+            // Ignore errors caused by simultaneous access.
+            // We intend to investigate/revert this in bug 1810212.
+            match writer.commit() {
+                Err(StoreError::IoError(e)) if e.kind() == std::io::ErrorKind::NotFound => {
+                    // Explicitly ignore errors from simultaneous access.
+                }
+                Err(e) => return Err(From::from(e)),
+                _ => (),
+            };
+
+            Ok(())
+        }()));
+    }
+
+    task_done!(void);
+}
+
+pub struct ClearTask {
+    callback: AtomicCell<Option<ThreadBoundRefPtr<nsIKeyValueVoidCallback>>>,
+    rkv: Arc<RwLock<Rkv>>,
+    store: SingleStore,
+    result: AtomicCell<Option<Result<(), KeyValueError>>>,
+}
+
+impl ClearTask {
+    pub fn new(
+        callback: RefPtr<nsIKeyValueVoidCallback>,
+        rkv: Arc<RwLock<Rkv>>,
+        store: SingleStore,
+    ) -> ClearTask {
+        ClearTask {
+            callback: AtomicCell::new(Some(ThreadBoundRefPtr::new(callback))),
+            rkv,
+            store,
+            result: AtomicCell::default(),
+        }
+    }
+}
+
+impl Task for ClearTask {
+    fn run(&self) {
+        // We do the work within a closure that returns a Result so we can
+        // use the ? operator to simplify the implementation.
+        self.result.store(Some(|| -> Result<(), KeyValueError> {
+            let env = self.rkv.read()?;
+            let mut writer = env.write()?;
+            self.store.clear(&mut writer)?;
+            // Ignore errors caused by simultaneous access.
+            // We intend to investigate/revert this in bug 1810212.
+            match writer.commit() {
+                Err(StoreError::IoError(e)) if e.kind() == std::io::ErrorKind::NotFound => {
+                    // Explicitly ignore errors from simultaneous access.
+                }
+                Err(e) => return Err(From::from(e)),
+                _ => (),
+            };
+
+            Ok(())
+        }()));
+    }
+
+    task_done!(void);
+}
+
+pub struct EnumerateTask {
+    callback: AtomicCell<Option<ThreadBoundRefPtr<nsIKeyValueEnumeratorCallback>>>,
+    rkv: Arc<RwLock<Rkv>>,
+    store: SingleStore,
+    from_key: nsCString,
+    to_key: nsCString,
+    result: AtomicCell<Option<Result<Vec<KeyValuePairResult>, KeyValueError>>>,
+}
+
+impl EnumerateTask {
+    pub fn new(
+        callback: RefPtr<nsIKeyValueEnumeratorCallback>,
+        rkv: Arc<RwLock<Rkv>>,
+        store: SingleStore,
+        from_key: nsCString,
+        to_key: nsCString,
+    ) -> EnumerateTask {
+        EnumerateTask {
+            callback: AtomicCell::new(Some(ThreadBoundRefPtr::new(callback))),
+            rkv,
+            store,
+            from_key,
+            to_key,
+            result: AtomicCell::default(),
+        }
+    }
+
+    fn convert(
+        &self,
+        result: Vec<KeyValuePairResult>,
+    ) -> Result<RefPtr<KeyValueEnumerator>, KeyValueError> {
+        Ok(KeyValueEnumerator::new(result))
+    }
+}
+
+impl Task for EnumerateTask {
+    fn run(&self) {
+        // We do the work within a closure that returns a Result so we can
+        // use the ? operator to simplify the implementation.
+        self.result.store(Some(
+            || -> Result<Vec<KeyValuePairResult>, KeyValueError> {
+                let env = self.rkv.read()?;
+                let reader = env.read()?;
+                let from_key = str::from_utf8(&self.from_key)?;
+                let to_key = str::from_utf8(&self.to_key)?;
+
+                let iterator = if from_key.is_empty() {
+                    self.store.iter_start(&reader)?
+                } else {
+                    self.store.iter_from(&reader, &from_key)?
+                };
+
+                // Ideally, we'd enumerate pairs lazily, as the consumer calls
+                // nsIKeyValueEnumerator.getNext(), which calls our
+                // KeyValueEnumerator.get_next() implementation.  But KeyValueEnumerator
+                // can't reference the Iter because Rust "cannot #[derive(xpcom)]
+                // on a generic type," and the Iter requires a lifetime parameter,
+                // which would make KeyValueEnumerator generic.
+                //
+                // Our fallback approach is to eagerly collect the iterator
+                // into a collection that KeyValueEnumerator owns.  Fixing this so we
+                // enumerate pairs lazily is bug 1499252.
+                let pairs: Vec<KeyValuePairResult> = iterator
+                    // Convert the key to a string so we can compare it to the "to" key.
+                    // For forward compatibility, we don't fail here if we can't convert
+                    // a key to UTF-8.  Instead, we store the Err in the collection
+                    // and fail lazily in KeyValueEnumerator.get_next().
+                    .map(|result| match result {
+                        Ok((key, val)) => Ok((str::from_utf8(&key), val)),
+                        Err(err) => Err(err),
+                    })
+                    // Stop iterating once we reach the to_key, if any.
+                    .take_while(|result| match result {
+                        Ok((key, _val)) => {
+                            if to_key.is_empty() {
+                                true
+                            } else {
+                                match *key {
+                                    Ok(key) => key < to_key,
+                                    Err(_err) => true,
+                                }
+                            }
+                        }
+                        Err(_) => true,
+                    })
+                    // Convert the key/value pair to owned.
+                    .map(|result| match result {
+                        Ok((key, val)) => match (key, val) {
+                            (Ok(key), val) => Ok((key.to_owned(), OwnedValue::from(&val))),
+                            (Err(err), _) => Err(err.into()),
+                        },
+                        Err(err) => Err(KeyValueError::StoreError(err)),
+                    })
+                    .collect();
+
+                Ok(pairs)
+            }(),
+        ));
+    }
+
+    task_done!(value);
+}