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//! Determine when to flush a block.

use crate::table::BlockBasedTableOptions;

/// FlushBlockPolicy provides a configurable way to determine when to flush a
/// block in the block based tables,
pub trait FlushBlockPolicy {
    /// Keep track of the key/value sequences and return the boolean value to
    /// determine if table builder should flush current data block.
    fn update(&mut self, key: &[u8], value: &[u8]) -> bool;
}

pub trait FlushBlockPolicyFactory {
    /// Return the name of the flush block policy.
    fn name(&self) -> &str {
        "RustFlushBlockPolicyFactory\0"
    }

    /// Return a new block flush policy that flushes data blocks by data size.
    /// FlushBlockPolicy may need to access the metadata of the data block
    /// builder to determine when to flush the blocks.
    ///
    /// Callers must delete the result after any database that is using the
    /// result has been closed.
    fn new_flush_block_policy(&self, table_options: &BlockBasedTableOptions) -> Box<dyn FlushBlockPolicy>;
}