Struct ConnPool

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pub struct ConnPool { /* private fields */ }

Expand description

SQLite connection pool.

This is a specialized connection pool that is defined specifically for sqlite, and only allows a single writer but multiple readers.

Implementations§

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impl ConnPool

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pub fn size(&self) -> usize

Return the pool size.

In effect, this is the size of the read-only pool plus one (for the read/write connection).

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pub fn reader(&self) -> Result<PooledConnection<SqliteConnectionManager>, Error>

Acquire a read-only connection.

§Errors

r2d2::Error will be returned if a read-only connection could not be acquired.

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pub fn writer(&self) -> WrConn

Acquire the read/write connection.

If the writer is already taken, then block and wait for it to become available.

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pub fn try_writer(&self) -> Option<WrConn>

Attempt to acquire the writer connection.

Returns Some(conn) if the writer connection was available at the time of the request. Returns None if the writer has already been taken.

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impl ConnPool

Special queries.

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pub fn freelist_count(&self) -> Result<usize, Error>

Return the number of unused pages.

§Errors

Error::R2D2 indicates that it wasn’t possible to acquire a read-only connection from the connection pool. Error::Sqlite means it was not possible to query the free page list count.

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impl ConnPool

Read-only connection processing.

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pub fn run_ro<T, F, E>(&self, f: F) -> Result<T, E>
where T: Send + 'static, F: FnOnce(&Connection) -> Result<T, E> + Send + 'static, E: From<Error>,

Run a read-only database operation.

§Errors

The error type E is used to return application-defined errors, though it must be possible to convert a r2d2::Error into E using the From trait.

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pub fn run_ro_thrd<F>(&self, f: F) -> Result<(), Error>
where F: FnOnce(&Connection) + Send + 'static,

Available on crate feature tpool only.

Run a read-only database operation on a thread.

§Errors

r2d2::Error is returned if it wasn’t possible to acquire a read-only connection from the connection pool.

§Panics

A thread pool must be associated with the ConnPool or this method will panic.

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pub fn run_ro_thrd_result<T, E, F>( &self, f: F, ) -> Result<WaitCtx<T, (), E>, Error>
where T: Send + 'static, E: Debug + Send + 'static, F: FnOnce(&Connection) -> Result<T, E> + Send + 'static,

Available on crate feature tpool only.

Run a read-only database operation on a thread, allowing the caller to receive the Result<T, E> of the supplied closure using a one-shot channel.

The supplied closure in f should return a Result<T, E> where the Ok case will be passed as a “set” value through the swctx channel, and the Err case will be passed as a “fail” value.

§Errors

r2d2::Error is returned if it wasn’t possible to acquire a read-only connection from the connection pool.

§Panics

A thread pool must be associated with the ConnPool or this method will panic.

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impl ConnPool

Read/Write connection processing.

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pub fn run_rw<T, E, F>(&self, f: F) -> Result<T, E>
where T: Send + 'static, E: Debug + Send + 'static, F: FnOnce(&mut WrConn) -> Result<T, E> + Send + 'static,

Run a read/write database operation.

§Errors

Returns an application-specific type E on error.

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pub fn run_rw_thrd<F>(&self, f: F)
where F: FnOnce(&mut WrConn) -> Option<usize> + Send + 'static,

Available on crate feature tpool only.

Run a read/write database operation on a thread.

The supplied closure should return an Option<usize>, where the Some() case denotes the specified amount of “dirt” should be added to the write connection. None means no dirt should be added.

§Panics

A thread pool must be associated with the ConnPool or this method will panic.

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pub fn run_rw_thrd_result<T, E, F>(&self, f: F) -> WaitCtx<T, (), E>
where T: Send + 'static, E: Debug + Send + 'static, F: FnOnce(&mut WrConn) -> Result<T, E> + Send + 'static,

Available on crate feature tpool only.

Run a read/write database operation on a thread, allowing the caller to receive the Result<T, E> of the supplied closure using a one-shot channel.

The supplied closure in f should return a Result<T, E> where the Ok case will be passed as a “set” value through the swctx channel, and the Err case will be passed as a “fail” value.