// Copyright 2015-2020 Parity Technologies (UK) Ltd.
// This file is part of OpenEthereum.

// OpenEthereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// OpenEthereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.

use std::cmp::max;

const MIN_BC_CACHE_MB: u32 = 4;
const MIN_DB_CACHE_MB: u32 = 8;
const MIN_BLOCK_QUEUE_SIZE_LIMIT_MB: u32 = 16;
const DEFAULT_DB_CACHE_SIZE: u32 = 128;
const DEFAULT_BC_CACHE_SIZE: u32 = 8;
const DEFAULT_BLOCK_QUEUE_SIZE_LIMIT_MB: u32 = 40;
const DEFAULT_TRACE_CACHE_SIZE: u32 = 20;
const DEFAULT_STATE_CACHE_SIZE: u32 = 25;

/// Configuration for application cache sizes.
/// All	values are represented in MB.
#[derive(Debug, PartialEq)]
pub struct CacheConfig {
    /// Size of rocksDB cache. Almost all goes to the state column.
    db: u32,
    /// Size of blockchain cache.
    blockchain: u32,
    /// Size of transaction queue cache.
    queue: u32,
    /// Size of traces cache.
    traces: u32,
    /// Size of the state cache.
    state: u32,
}

impl Default for CacheConfig {
    fn default() -> Self {
        CacheConfig::new(
            DEFAULT_DB_CACHE_SIZE,
            DEFAULT_BC_CACHE_SIZE,
            DEFAULT_BLOCK_QUEUE_SIZE_LIMIT_MB,
            DEFAULT_STATE_CACHE_SIZE,
        )
    }
}

impl CacheConfig {
    /// Creates new cache config with cumulative size equal `total`.
    pub fn new_with_total_cache_size(total: u32) -> Self {
        CacheConfig {
            db: total * 7 / 10,
            blockchain: total / 10,
            queue: DEFAULT_BLOCK_QUEUE_SIZE_LIMIT_MB,
            traces: DEFAULT_TRACE_CACHE_SIZE,
            state: total * 2 / 10,
        }
    }

    /// Creates new cache config with gitven details.
    pub fn new(db: u32, blockchain: u32, queue: u32, state: u32) -> Self {
        CacheConfig {
            db: db,
            blockchain: blockchain,
            queue: queue,
            traces: DEFAULT_TRACE_CACHE_SIZE,
            state: state,
        }
    }

    /// Size of db cache.
    pub fn db_cache_size(&self) -> u32 {
        max(MIN_DB_CACHE_MB, self.db)
    }

    /// Size of block queue size limit
    pub fn queue(&self) -> u32 {
        max(self.queue, MIN_BLOCK_QUEUE_SIZE_LIMIT_MB)
    }

    /// Size of the blockchain cache.
    pub fn blockchain(&self) -> u32 {
        max(self.blockchain, MIN_BC_CACHE_MB)
    }

    /// Size of the traces cache.
    pub fn traces(&self) -> u32 {
        self.traces
    }

    /// Size of the state cache.
    pub fn state(&self) -> u32 {
        self.state * 3 / 4
    }

    /// Size of the jump-tables cache.
    pub fn jump_tables(&self) -> u32 {
        self.state / 4
    }
}

#[cfg(test)]
mod tests {
    use super::CacheConfig;

    #[test]
    fn test_cache_config_constructor() {
        let config = CacheConfig::new_with_total_cache_size(200);
        assert_eq!(config.db, 140);
        assert_eq!(config.blockchain(), 20);
        assert_eq!(config.queue(), 40);
        assert_eq!(config.state(), 30);
        assert_eq!(config.jump_tables(), 10);
    }

    #[test]
    fn test_cache_config_db_cache_sizes() {
        let config = CacheConfig::new_with_total_cache_size(400);
        assert_eq!(config.db, 280);
        assert_eq!(config.db_cache_size(), 280);
    }

    #[test]
    fn test_cache_config_default() {
        assert_eq!(
            CacheConfig::default(),
            CacheConfig::new(
                super::DEFAULT_DB_CACHE_SIZE,
                super::DEFAULT_BC_CACHE_SIZE,
                super::DEFAULT_BLOCK_QUEUE_SIZE_LIMIT_MB,
                super::DEFAULT_STATE_CACHE_SIZE
            )
        );
    }
}
