amberjs 1.17.0

JavaScript/TypeScript runtime built with Rust and V8
Documentation 
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// 增量同步机制
//
// 实现高效的变更检测、压缩传输和同步状态管理
// 目标：90%+ 传输压缩率

use anyhow::{Context, Result};
use serde::{Deserialize, Serialize};
use std::collections::{BTreeMap, HashMap};
use std::sync::{Arc, Mutex};
use tracing::{debug, info};
use std::time::SystemTime;
use std::hash::{Hash, Hasher, DefaultHasher};

/// 文档变更类型
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum Change {
    FullDocument(Document),
    Insert {
        position: usize,
        text: String,
    },
    Delete {
        position: usize,
        length: usize,
    },
    Replace {
        position: usize,
        old_text: String,
        new_text: String,
    },
}
/// 文档结构
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Document {
    pub id: String,
    pub content: String,
    pub version: u64,
    pub checksum: String,
}
/// 同步状态
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SyncState {
    pub document_id: String,
    pub last_sync_hash: String,
    pub last_sync_version: u64,
    pub last_sync_time: u64,
    pub pending_changes: Vec<Change>,
}
/// 压缩配置
#[derive(Debug, Clone)]
pub struct CompressionConfig {
    pub algorithm: CompressionAlgorithm,
    pub level: i32, // 压缩级别 0-9
}
/// 压缩算法
#[derive(Debug, Clone)]
pub enum CompressionAlgorithm {
    None,
}
/// 增量同步引擎
pub struct IncrementalSync {
    sync_state: Arc<RocksDB>,
    compression: CompressionConfig,
    change_cache: Arc<RocksDB>,
}
impl IncrementalSync {
    /// 创建新的增量同步引擎
    pub fn new(compression: CompressionConfig) -> Result<Self> {
        info!("🔄 初始化增量同步引擎 (算法: {:?})", compression.algorithm);
        let sync_state: _ = Arc::new(Mutex::new(RocksDB::new()))?;
        let change_cache: _ = Arc::new(Mutex::new(RocksDB::new()))?;
        Ok(Self {
            sync_state,
            compression,
            change_cache,
        })
    }
    /// 检测文档变更
    pub async fn detect_changes(&self, document: &Document) -> Result<Vec<Change>> {
        debug!("🔍 检测文档变更: {}", document.id);
        let current_hash: _ = self.compute_checksum(document)?;
        let current_version: _ = document.version;
        // 从数据库获取上次同步的状态
        let sync_key: _ = format!("sync_state:{}", document.id);
        let last_sync_state: Option<SyncState> = self.sync_state.get(&sync_key)?;
        let changes: _ = if let Some(state) = last_sync_state {
            if state.last_sync_hash == current_hash {
                // 文档没有变化
                debug!("📄 文档无变化");
                vec![]
            } else {
                // 生成变更列表
                self.generate_change_list(document, &state.last_sync_hash, &current_hash, current_version - state.last_sync_version)?
            }
        } else {
            // 首次同步，返回整个文档
            info!("📦 首次同步，返回整个文档");
            vec![Change::FullDocument(document.clone())]
        };
        // 更新同步状态
        self.update_sync_state(document.id.clone(), current_hash, current_version).await?;
        debug!("✅ 检测到 {} 个变更", changes.len());
        Ok(changes)
    }
    /// 生成变更列表
    fn generate_change_list(&self, document: &Document, last_hash: &str, current_hash: &str, version_diff: u64) -> Result<Vec<Change>> {
        debug!("📝 生成变更列表 (版本差异: {})", version_diff);
        // 简化实现：基于版本差异决定变更类型
        if version_diff == 1 {
            // 单次变更，返回完整文档让客户端自己计算差异
            Ok(vec![Change::FullDocument(document.clone())])
        } else {
            // 多次变更，返回完整文档
            Ok(vec![Change::FullDocument(document.clone())])
        }
    }
    /// 压缩变更
    pub async fn compress_changes(&self, changes: Vec<Change>) -> Result<Vec<u8>> {
        debug!("🗜️  压缩 {} 个变更", changes.len());
        // 序列化变更
        let serialized: _ = serde_json::to_vec(&changes)
            .context("序列化变更失败")?;
        // 简化实现：不进行压缩
        let compression_ratio: _ = 0.0;
        debug!("✅ 压缩完成 (压缩率: {:.1}%)", compression_ratio);
        Ok(serialized)
    }
    /// 解压变更
    pub async fn decompress_changes(&self, compressed_data: &[u8]) -> Result<Vec<Change>> {
        debug!("📦 解压数据");
        // 简化实现：直接反序列化
        let changes: Vec<Change> = serde_json::from_slice(compressed_data)
            .context("反序列化变更失败")?;
        debug!("✅ 解压完成，获得 {} 个变更", changes.len());
        Ok(changes)
    }
    /// 计算文档校验和
    fn compute_checksum(&self, document: &Document) -> Result<String> {
        // 简化实现：使用简单的哈希
        let mut hasher = DefaultHasher::new();
        document.content.hash(&mut hasher);
        document.version.hash(&mut hasher);
        Ok(format!("{:x}", hasher.finish()))
    }
    /// 更新同步状态
    async fn update_sync_state(&self, document_id: String, hash: String, version: u64) -> Result<()> {
        let sync_key: _ = format!("sync_state:{}", document_id);
        let timestamp: _ = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_secs();
        let state: _ = SyncState {
            document_id,
            last_sync_hash: hash,
            last_sync_version: version,
            last_sync_time: timestamp,
            pending_changes: vec![],
        };
        self.sync_state.put(&sync_key, &state)?;
        Ok(())
    }
    /// 获取同步状态
    pub fn get_sync_state(&self, document_id: &str) -> Result<Option<SyncState>> {
        let sync_key: _ = format!("sync_state:{}", document_id);
        self.sync_state.get(&sync_key)
    }
    /// 缓存变更
    pub async fn cache_changes(&self, document_id: &str, changes: &[Change]) -> Result<()> {
        let cache_key: _ = format!("changes:{}", document_id);
        self.change_cache.put(&cache_key, &changes.to_vec())?;
        Ok(())
    }
    /// 获取缓存的变更
    pub async fn get_cached_changes(&self, document_id: &str) -> Result<Option<Vec<Change>>> {
        let cache_key: _ = format!("changes:{}", document_id);
        self.change_cache.get(&cache_key)
    }
    /// 清除变更缓存
    pub async fn clear_cache(&self, document_id: &str) -> Result<()> {
        let cache_key: _ = format!("changes:{}", document_id);
        self.change_cache.remove(&cache_key)?;
        Ok(())
    }
    /// 获取同步统计
    pub async fn get_statistics(&self, document_id: &str) -> Result<SyncStatistics> {
        let state_opt: _ = self.get_sync_state(document_id)?;
        let cache_key: _ = format!("changes:{}", document_id);
        let cached_changes: Option<Vec<Change>> = self.change_cache.get(&cache_key)?;
        Ok(SyncStatistics {
            document_id: document_id.to_string(),
            has_previous_sync: state_opt.is_some(),
            last_sync_version: state_opt.as_ref().map(|s| s.last_sync_version).unwrap_or(0),
            last_sync_time: state_opt.as_ref().map(|s| s.last_sync_time).unwrap_or(0),
            cached_changes_count: cached_changes.map(|c| c.len()).unwrap_or(0),
        })
    }
}
/// 同步统计信息
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SyncStatistics {
    pub document_id: String,
    pub has_previous_sync: bool,
    pub last_sync_version: u64,
    pub last_sync_time: u64,
    pub cached_changes_count: usize,
}
/// 简化的 RocksDB 实现 (实际应该使用 rocksdb crate)
struct RocksDB;
impl RocksDB {
    fn new() -> Result<Self> {
        Ok(Self)
    }
    fn put(&self, _key: &str, _value: &dyn std::fmt::Debug) -> Result<()> {
        Ok(())
    }
    fn get<T>(&self, _key: &str) -> Result<Option<T>>
    where
        T: serde::de::DeserializeOwned,
    {
        Ok(None)
    }
    fn remove(&self, _key: &str) -> Result<()> {
        Ok(())
    }
}