Refactor and Add SkipSet

Refactor implementation and add more convenient APIs

.codecov.yml

@@ -0,0 +1,24 @@
+codecov:
+  require_ci_to_pass: false
+
+ignore:
+  - integration/
+
+coverage:
+  status:
+    project: # Overall project status
+      default:
+        target: auto
+        if_not_found: success
+        only_pulls: false
+    patch: # Status for the patch in pull requests
+      default:
+        target: auto
+        if_not_found: success
+        only_pulls: true
+    changes: false # Whether to comment on the coverage changes in pull requests
+
+comment:
+  layout: "header, diff, files, footer"
+  behavior: default
+  require_changes: false

.github/workflows/ci.yml

@@ -20,6 +20,7 @@ on:
       - "LICENSE-*"
       - "**.md"
       - "**.txt"
+  workflow_dispatch:
 
 env:
   CARGO_TERM_COLOR: always
@@ -130,7 +131,7 @@ jobs:
       - name: cargo build --target ${{ matrix.target }}
         run: |
           rustup target add ${{ matrix.target }}
-          cargo build --features js --target ${{ matrix.target }}
+          cargo build --target ${{ matrix.target }}
         if: matrix.target == 'wasm32-unknown-unknown'
       # - name: cargo build --target ${{ matrix.target }}
       #   run: |
@@ -149,7 +150,7 @@ jobs:
       - name: Install rust-src
         run: rustup component add rust-src
       - name: ASAN / LSAN / TSAN
-        run: . ci/sanitizer.sh
+        run: ci/sanitizer.sh
 
   # valgrind
   valgrind:
@@ -169,21 +170,20 @@ jobs:
           sudo apt-get update -y
           sudo apt-get install -y valgrind
       # Compile tests
-      - name: cargo build test-fixed
-        run: cargo build --bin test-fixed
-        working-directory: integration
-
-      # Run with valgrind
-      - name: Run valgrind test-vec
-        run: valgrind --error-exitcode=1 --leak-check=full --show-leak-kinds=all ./target/debug/test-vec
+      - name: build & valgrind (vec backend)
+        run: |
+          cargo build --bin test-vec --target-dir .
+          valgrind --error-exitcode=1 --leak-check=full --show-leak-kinds=all ./debug/test-vec
         working-directory: integration
-
-      - name: Run valgrind test-mmap
-        run: valgrind --error-exitcode=1 --leak-check=full --show-leak-kinds=all ./target/debug/test-mmap
+      - name: build & valgrind (mmap backend)
+        run: |
+          cargo build --bin test-mmap --target-dir .
+          valgrind --error-exitcode=1 --leak-check=full --show-leak-kinds=all ./debug/test-mmap 
         working-directory: integration
-
-      - name: Run valgrind test-mmap-anon
-        run: valgrind --error-exitcode=1 --leak-check=full --show-leak-kinds=all ./target/debug/test-mmap-anon
+      - name: build & valgrind (mmap-anon backend)
+        run: |
+          cargo build --bin test-mmap-anon --target-dir .
+          valgrind --error-exitcode=1 --leak-check=full --show-leak-kinds=all ./debug/test-mmap-anon 
         working-directory: integration
 
 
@@ -195,16 +195,15 @@ jobs:
       - name: Miri
         run: ci/miri.sh
 
-  # Loom
   # loom:
   #   name: loom
   #   runs-on: ubuntu-latest
   #   steps:
-  #     - uses: actions/checkout@v3
+  #     - uses: actions/checkout@v4
   #     - name: Install Rust
   #       run: rustup update $nightly && rustup default $nightly
   #     - name: Loom tests
-  #       run: RUSTFLAGS="--cfg loom -Dwarnings" cargo test --test loom
+  #       run: RUSTFLAGS="--cfg loom -Dwarnings" cargo test --lib
 
   coverage:
     name: cargo tarpaulin
@@ -215,8 +214,7 @@ jobs:
       - stable
       - nightly
       - sanitizer
-      - valgrind
-      - miri
+      - valgrind 
       - minrust
     steps:
       - uses: actions/checkout@v3
@@ -243,7 +241,7 @@ jobs:
         uses: actions-rs/cargo@v1
         with:
           command: tarpaulin
-          args: --run-types Tests,Doctests --workspace --out Xml
+          args: --all-features --run-types tests --run-types doctests --workspace --out xml
       - name: Upload to codecov.io
         uses: codecov/codecov-action@v3.1.1
         with:

.github/workflows/loc.yml

@@ -0,0 +1,58 @@
+name: loc 
+
+on:
+  push:
+    branches:
+      - main
+    paths-ignore:
+      - 'README.md'
+      - 'COPYRIGHT'
+      - 'LICENSE*'
+      - '**.md'
+      - '**.txt'
+      - 'art'
+  pull_request:
+    paths-ignore:
+      - 'README.md'
+      - 'COPYRIGHT'
+      - 'LICENSE*'
+      - '**.md'
+      - '**.txt'
+      - 'art'
+  workflow_dispatch:
+
+jobs:
+  loc:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Install Rust
+        run: |
+          rustup update stable && rustup default stable
+          rustup component add clippy
+          rustup component add rustfmt
+      
+      - name: Install tokeit
+        run: |
+          cargo install tokeit --force
+      
+      - name: Count total lines of code
+        run: |
+          tokeit
+      - name: Upload total loc to GitHub Gist
+        uses: actions/github-script@v6
+        with:
+          github-token: ${{ secrets.GIST_PAT }}
+          script: |
+            const fs = require('fs');
+            const output = fs.readFileSync('tokeit.json', 'utf8');
+            const gistId = '327b2a8aef9003246e45c6e47fe63937';
+            await github.rest.gists.update({
+              gist_id: gistId,
+              files: {
+                "skl": {
+                  content: output
+                }
+              }
+            });

Cargo.toml

@@ -3,7 +3,7 @@ name = "skl"
 version = "0.4.0"
 edition = "2021"
 repository = "https://github.com/al8n/skl-rs"
-description = "A lock-free thread-safe concurrent ARENA based skiplist implementation which helps develop MVCC memtable for LSM-Tree. Inspired by Dgraph's badger https://github.com/dgraph-io/badger/tree/main/skl."
+description = "A lock-free thread-safe concurrent ARENA based (heap backend or memory map backend) skiplist implementation which helps develop MVCC memtable for LSM-Tree."
 documentation = "https://docs.rs/skl"
 homepage = "https://github.com/al8n/skl-rs"
 keywords = ["skiplist", "lock-free", "memtable", "concurrency", "arena"]
@@ -15,35 +15,48 @@ path = "benches/bench.rs"
 name = "bench"
 harness = false
 
-[[test]]
-path = "tests/loom.rs"
-name = "loom"
+[[example]]
+name = "heap"
+path = "examples/heap.rs"
+
+[[example]]
+name = "mmap"
+path = "examples/mmap.rs"
+required-features = ["memmap"]
+
+[[example]]
+name = "mmap-anon"
+path = "examples/mmap_anon.rs"
+required-features = ["memmap"]
 
 [features]
 default = ["std"]
 alloc = []
-mmap = ["memmapix", "fs4", "std"]
-std = ["bytes/std", "rand/std", "rand/std_rng", "inline_more"]
-inline_more = []
-js = ["getrandom/js"]
+memmap = ["memmap2", "fs4", "std"]
+std = ["rand/default"]
 
 [target.'cfg(loom)'.dependencies]
 loom = "0.7"
 
+[target.'cfg(target_family = "wasm")'.dependencies]
+getrandom = { version = "0.2", features = ["js"] }
+rand = { version = "0.8", default-features = false, features = ["getrandom"] }
+
+[target.'cfg(not(target_family = "wasm"))'.dependencies]
+rand = { version = "0.8", default-features = false }
+
 [dependencies]
-bytes = { version = "1.5", default-features = false }
 crossbeam-utils = { version = "0.8", default-features = false }
-fs4 = { version = "0.6", optional = true }
-getrandom = { version = "0.2", optional = true }
-memmapix = { version = "0.7", optional = true }
-rand = { version = "0.8", default-features = false, features = ["getrandom"] }
-viewit = "0.1.5"
+
+fs4 = { version = "0.8", optional = true }
+memmap2 = { version = "0.9", optional = true }
 
 [dev-dependencies]
 criterion = "0.5"
 tempfile = "3"
 parking_lot = "0.12"
 paste = "1"
+wg = { version = "0.9", default-features = false, features = ["std"] }
 
 [profile.bench]
 opt-level = 3
@@ -58,3 +71,6 @@ rpath = false
 [package.metadata.docs.rs]
 all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
+
+[workspace]
+members = ["integration"]

README.md

@@ -4,61 +4,51 @@
 
 <div align="center">
 
-[<img alt="github" src="https://img.shields.io/badge/github-skl--rs-8da0cb?style=for-the-badge&logo=Github" height="22">][Github-url]
+[<img alt="github" src="https://img.shields.io/badge/github-al8n/skl-8da0cb?style=for-the-badge&logo=Github" height="22">][Github-url]
+<img alt="LoC" src="https://img.shields.io/endpoint?url=https%3A%2F%2Fgist.githubusercontent.com%2Fal8n%2F327b2a8aef9003246e45c6e47fe63937%2Fraw%2Fskl" height="22">
 [<img alt="Build" src="https://img.shields.io/github/actions/workflow/status/al8n/skl-rs/ci.yml?style=for-the-badge&logo=Github-Actions&label=CI" height="22">][CI-url]
 [<img alt="codecov" src="https://img.shields.io/codecov/c/gh/al8n/skl-rs?style=for-the-badge&token=aek5JwyaAZ&logo=codecov" height="22">][codecov-url]
 
 [<img alt="docs.rs" src="https://img.shields.io/badge/docs.rs-skl-66c2a5?style=for-the-badge&labelColor=555555&logo=data:image/svg+xml;base64,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" height="20">][doc-url]
 [<img alt="crates.io" src="https://img.shields.io/crates/v/skl?style=for-the-badge&logo=data:image/svg+xml;base64,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" height="22">][crates-url]
-[<img alt="rustc" src="https://img.shields.io/badge/MSRV-1.72.0-fc8d62.svg?style=for-the-badge&logo=Rust" height="22">][rustc-url]
+<img alt="license" src="https://img.shields.io/badge/License-Apache%202.0/MIT-blue.svg?style=for-the-badge&fontColor=white&logoColor=f5c076&logo=data:image/svg+xml;base64,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" height="22">
 
-[<img alt="license-apache" src="https://img.shields.io/badge/License-Apache%202.0-blue.svg?style=for-the-badge&logo=Apache" height="22">][license-apache-url]
-[<img alt="license-mit" src="https://img.shields.io/badge/License-MIT-yellow.svg?style=for-the-badge&fontColor=white&logoColor=f5c076&logo=data:image/svg+xml;base64,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" height="22">][license-mit-url]
-
-A lock-free thread-safe concurrent ARENA based skiplist implementation which helps develop MVCC memtable for LSM-Tree. Inspired by [Dgraph's badger](https://github.com/dgraph-io/badger/tree/main/skl).
+1. A lock-free thread-safe concurrent `SkipMap` and `SkipSet` implementation based on ARENA skiplist which helps develop MVCC memtable for LSM-Tree.
+2. A lock-free thread-safe concurrent memory map based on-disk `SkipMap` and `SkipSet`.
 
 </div>
 
 ## Installation
 
-```toml
-[dependencies]
-skl = "0.3"
-```
-
-## Example
-
-```rust
-use skl::SkipMap;
-use std::sync::Arc;
-
-fn main() {
-    const N: usize = 1000;
-    let l = Arc::new(SkipMap::new(1 << 20));
-    let wg = Arc::new(());
-    for i in 0..N {
-        let w = wg.clone();
-        let l = l.clone();
-        std::thread::spawn(move || {
-            l.insert(key(i), new_value(i));
-            drop(w);
-        });
-    }
-    while Arc::strong_count(&wg) > 1 {}
-    for i in 0..N {
-        let w = wg.clone();
-        let l = l.clone();
-        std::thread::spawn(move || {
-            assert_eq!(
-                l.get(key(i)).unwrap().as_value_ref(),
-                new_value(i).as_value_ref(),
-                "broken: {i}"
-            );
-            drop(w);
-        });
-    }
-}
-```
+- Only use heap backend (suppport `no_std`)
+
+    ```toml
+    [dependencies]
+    skl = "0.4"
+    ```
+
+- Enable memory map backend
+
+    ```toml
+    [dependencies]
+    skl = { version = "0.4", features = ["memmap"] }
+    ```
+
+## Features
+
+- **Lock-free and Concurrent-Safe:** SkipMap and SkipSet provide lock-free operations, ensuring efficient concurrent access without the need for explicit locking mechanisms.
+- **Extensible for Key-Value Database Developers:** Designed as a low-level crate, SkipMap and SkipSet offer a flexible foundation for key-value database developers. You can easily build your own memtable or write-ahead-log (WAL) using these structures.
+- **Memory Efficiency:** These data structures are optimized for minimal memory overhead. They operate around references, avoiding unnecessary allocations and deep copies, which can be crucial for efficient memory usage.
+- **Efficient Iteration:** Enjoy fast forward and backward iteration through the elements in your SkipMap or SkipSet. Additionally, bounded iterators are supported, allowing you to traverse only a specified range of elements efficiently.
+- **Snapshot Support:** Create snapshots of your SkipMap or SkipSet, offering a read-only view of the contents at a specific moment in time. Snapshots provide a consistent view of the data, enabling implementations of transactional semantics and other use cases where data consistency is crucial.
+- **Memory Management Options:**
+  - **Heap Allocation:** Memory allocation is handled by Rust's allocator, ensuring all data resides in RAM.
+  - **Mmap:** Data can be mapped to a disk file by the operating system, making it suitable for write-ahead-logs (WAL) and durable storage.
+  - **Mmap Anonymous:** Mapped to anonymous memory (virtual memory) by the OS, ideal for large in-memory memtables, optimizing memory utilization.
+
+## Examples
+
+Please see [examples](https://github.com/al8n/skl-rs/tree/main/examples) folder for more details.
 
 ## Tests
 
@@ -93,17 +83,29 @@ fn main() {
 | x86_64-pc-windows-gnu         |  &#9989;  |
 | x86_64-linux-android          |  &#9989;  |
 
+## Pedigree
+
+This code is inspired and modified based on Cockroachdb's pebble arenaskl code:
+
+https://github.com/cockroachdb/pebble/tree/master/internal/arenaskl
+
+The pebble's arenaskl code is based on Andy Kimball's arenaskl code:
+
+https://github.com/andy-kimball/arenaskl
+
+The arenaskl code is based on the skiplist found in Badger, a Go-based
+KV store:
+
+https://github.com/dgraph-io/badger/tree/master/skl
+
+The skiplist in Badger is itself based on a C++ skiplist built for
+Facebook's RocksDB:
+
+https://github.com/facebook/rocksdb/tree/master/memtable
+
 ## TODO (help wanted)
 
-- [x] make the crate test cases pass `cargo miri`
 - [ ] make the crate test cases pass `cargo loom`
-- [ ] Implement
-  - [ ] `std::iter::Iterator`
-  - [ ] `get_or_insert`
-  - [ ] `remove`
-  - [ ] `contains`
-  - [ ] change signature from `insert(k, v)` => `insert(k, v) -> Option<ValueRef>`
-  - [ ] mmap backend (currently is vector backend)
 
 #### License