Cache

LevelDB cache

By default, Warp uses LevelDB to cache the state and contracts (metadata, source code, etc).

During the state evaluation, state is then evaluated only for the interactions that the state hasn't been evaluated yet.

info

State is being cached per transaction (i.e. its sort key) and NOT per block height.

Each contract may have multiple transactions at any given block height - that's why caching by block height is not sufficient - especially when contracts interact with each other.

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The cache for contracts' state is implemented as sub-levels. The default location for the Node.js cache is ./cache/warp.

info

In the browser environment Warp uses IndexedDB to cache the state - it's a low-level API for client-side storage. The default name for the browser IndexedDB cache is warp-cache.

In order to reduce the cache size, the oldest entries are automatically pruned.

tip

It is possible to use the in-memory cache instead by setting cacheOptions.inMemory to true while initializing Warp. inMemory cache is used by default in local environment.

tip

You can also supply your own implementation of the SortKeyCache interface and use them as a state and contracts cache. In order to use custom implementation call either useStateCache or useContractCache on warp instance.

LMDB cache

Warp Contracts implementation of the SortKeyCache using the LMDB database.

tip

LMDB is a much better solution (than LevelDB) in terms of read/write access times and concurrent access. Comparison by Mozilla.

Installation

caution

LMDB based cache is compatible only with Node.js env.

yarn add warp-contracts-lmdb

info

Requires warp-contracts SDK ver. min. 1.2.17

Custom options

LmdbCache constructor accepts a second param with custom configuration.

Option	Required	Description
maxEntriesPerContract	false	Maximum number of interactions stored per contract id - above this threshold adding another entry triggers removing old interactions.
minEntriesPerContract	false	Minimum number of interactions stored per contract id. Value used when removing old interactions.

Usage

const {defaultCacheOptions, WarpFactory} = require("warp-contracts");
const {LmdbCache} = require("warp-contracts-lmdb");

const warp = WarpFactory
  .forMainnet()
  .useStateCache(new LmdbCache({
      ...defaultCacheOptions,
      dbLocation: `./cache/warp/state`
    }, {
      maxEntriesPerContract: 100, 
      minEntriesPerContract: 10
    }
  ))
  .useContractCache(
    // Contract cache
    new LmdbCache({
    ...defaultCacheOptions,
    dbLocation: `./cache/warp/contracts`
    }), 
    // Source cache
    new LmdbCache({
    ...defaultCacheOptions,
    dbLocation: `./cache/warp/src`
  }));

SQLite cache

Warp Contracts implementation of the BasicSortKeyCache using the better-sqlite3 database.

tip

warp-contracts-sqlite uses incremental auto vacuum mode to reduce the size of the storage.

One of the disadvantages of LMDB is its size. Although Warp LmdbCache implements data pruning to reduce the number of stored entries, the LMDB storage only increases in size over time.

Since state caching is crucial in D.R.E. nodes, state cache efficiency and size is very important. These factors have driven us to create yet another cache implementation. This time with a help of better-sqlite3.

This implementation uses:

• Incremental auto vacuum mode, which means that the sqlite will reuse space marked as deleted,
• WAL mode, which greatly improves concurrent read and writes performance.

Installation

caution

SQLite based cache is compatible only with Node.js env.

yarn add warp-contracts-sqlite

Custom options

SqliteContractCache constructor accepts a second param with custom configuration.

Option	Required	Description
maxEntriesPerContract	false	Maximum number of interactions stored per contract id - above this threshold adding another entry triggers removing old interactions.

Usage

    const warp = WarpFactory.forMainnet().useStateCache(
    new SqliteContractCache(
      {
        ...defaultCacheOptions,
        dbLocation: `./cache/warp/sqlite/state`
      },
      {
        maxEntriesPerContract: 20
      }
    )
  )

info

Requires warp-contracts SDK ver. min. 1.4.7