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Store

planarian_txn::store

Trait Store 

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pub trait Store {
    type Guard;


Show 13 methods    // Required methods
    fn lock(&self) -> Result<Self::Guard>;
    fn capacity(&self) -> u64;
    fn read_at(&self, off: u64, len: usize) -> Result<Vec<u8>>;
    fn write_at(&self, off: u64, bytes: &[u8]) -> Result<()>;
    fn sync(&self) -> Result<()>;
    fn read_checkpoint(&self) -> Result<Option<Vec<u8>>>;
    fn write_checkpoint(&self, bytes: &[u8]) -> Result<()>;
    fn read_sentinel(&self) -> Result<Option<Vec<u8>>>;
    fn write_sentinel(&self, bytes: &[u8]) -> Result<()>;
    fn fence(&self, txn: TxnId) -> Result<Option<u64>>;
    fn set_fence(&self, txn: TxnId, epoch: u64) -> Result<()>;
    fn create_fence(&self, txn: TxnId, epoch: u64) -> Result<()>;
    fn forget_fences<F: Fn(TxnId) -> bool>(&self, keep: F) -> Result<Vec<TxnId>>;

}

Required Associated Types§

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type Guard

Held while a journal handle reads-then-appends; serializes all handles (across processes for FileStore). Released on drop.

Required Methods§

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fn lock(&self) -> Result<Self::Guard>

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fn capacity(&self) -> u64

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fn read_at(&self, off: u64, len: usize) -> Result<Vec<u8>>

Up to len bytes at off; shorter at the end of the preallocation.

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fn write_at(&self, off: u64, bytes: &[u8]) -> Result<()>

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fn sync(&self) -> Result<()>

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fn read_checkpoint(&self) -> Result<Option<Vec<u8>>>

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fn write_checkpoint(&self, bytes: &[u8]) -> Result<()>

Atomic: either the old checkpoint or the complete new one survives.

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fn read_sentinel(&self) -> Result<Option<Vec<u8>>>

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fn write_sentinel(&self, bytes: &[u8]) -> Result<()>

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fn fence(&self, txn: TxnId) -> Result<Option<u64>>

The epoch backends fence on. Written before the journal’s Takeover record.

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fn set_fence(&self, txn: TxnId, epoch: u64) -> Result<()>

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fn create_fence(&self, txn: TxnId, epoch: u64) -> Result<()>

A new transaction’s fence, created exclusively (§9 step 4, C5): fails with AlreadyExists if anything is already there for this id.

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fn forget_fences<F: Fn(TxnId) -> bool>(&self, keep: F) -> Result<Vec<TxnId>>

Removes the fence of every transaction keep rejects; returns them. A transaction without a fence is never admitted, so this only narrows.

Dyn Compatibility§

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors§