Removed custom allocator (#693)

.github/workflows/test.yml

@@ -88,27 +88,6 @@ jobs:
         # --skip io: miri can't handle opening of files, so we skip those
         run: cargo miri test --features full -- --skip io::parquet --skip io::ipc
 
-  miri-checks-custom-allocator:
-    name: MIRI with custom allocator
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: nightly-2021-12-10
-          override: true
-      - uses: Swatinem/rust-cache@v1
-        with:
-          key: key1
-      - name: Install Miri
-        run: |
-          rustup component add miri
-          cargo miri setup
-
-      - name: Run
-        # --skip io: miri can't handle opening of files, so we skip those
-        run: cargo miri test --features full,cache_aligned -- --skip io::parquet --skip io::ipc
-
   coverage:
     name: Coverage
     runs-on: ubuntu-latest
@@ -130,7 +109,6 @@ jobs:
         run: cargo install cargo-tarpaulin
       - name: Run coverage
         run: |
-          cargo tarpaulin --features cache_aligned --ignore-tests --out Xml
           cargo tarpaulin --features full --ignore-tests --out Xml
       - name: Report coverage
         continue-on-error: true

Cargo.toml

@@ -207,9 +207,6 @@ compute = [
 io_parquet = ["parquet2", "io_ipc", "base64", "futures"]
 benchmarks = ["rand"]
 simd = ["packed_simd"]
-# uses a custom allocator whose pointers are aligned along cache lines.
-# Using this features makes `Buffer` and `MutableBuffer` incompatible with `Vec`.
-cache_aligned = []
 
 [package.metadata.cargo-all-features]
 allowlist = ["compute", "compute_sort", "compute_hash", "compute_nullif"]
@@ -238,10 +235,6 @@ harness = false
 name = "count_zeros"
 harness = false
 
-[[bench]]
-name = "from_trusted_len_iter"
-harness = false
-
 [[bench]]
 name = "growable"
 harness = false

benches/iter_list.rs

@@ -6,7 +6,7 @@ use criterion::{criterion_group, criterion_main, Criterion};
 use arrow2::{
     array::{ListArray, PrimitiveArray},
     bitmap::Bitmap,
-    buffer::{Buffer, MutableBuffer},
+    buffer::Buffer,
     datatypes::DataType,
 };
 
@@ -17,7 +17,7 @@ fn add_benchmark(c: &mut Criterion) {
         let values = Buffer::from_iter(0..size as i32);
         let values = PrimitiveArray::<i32>::from_data(DataType::Int32, values, None);
 
-        let mut offsets = MutableBuffer::from_iter((0..size as i32).step_by(2));
+        let mut offsets = (0..size as i32).step_by(2).collect::<Vec<_>>();
         offsets.push(size as i32);
 
         let validity = (0..(offsets.len() - 1))

guide/src/low_level.md

@@ -20,7 +20,7 @@ These hold _all_ data-related memory in this crate.
 Due to their intrinsic immutability, each container has a corresponding mutable
 (and non-shareable) variant:
 
-* `MutableBuffer<T>`
+* `Vec<T>`
 * `MutableBitmap`
 
 Let's see how these structures are used.
@@ -30,43 +30,16 @@ Create a new `Buffer<u32>`:
 ```rust
 # use arrow2::buffer::Buffer;
 # fn main() {
-let x = Buffer::from(&[1u32, 2, 3]);
+let x = vec![1u32, 2, 3];
+let x: Buffer<u32> = x.into();
 assert_eq!(x.as_slice(), &[1u32, 2, 3]);
 
-let x = x.slice(1, 2);
+let x = x.slice(1, 2); // O(1)
 assert_eq!(x.as_slice(), &[2, 3]);
 # }
 ```
 
-Using a `MutableBuffer<i64>`:
-
-```rust
-# use arrow2::buffer::MutableBuffer;
-# fn main() {
-let mut x: MutableBuffer<i64> = (0..3).collect();
-x[1] = 5;
-x.push(10);
-assert_eq!(x.as_slice(), &[0, 5, 2, 10])
-# }
-```
-
-The following demonstrates how to efficiently
-perform an operation from an iterator of
-[TrustedLen](https://doc.rust-lang.org/std/iter/trait.TrustedLen.html):
-
-```rust
-# use arrow2::buffer::MutableBuffer;
-# fn main() {
-let x = (0..1000).collect::<Vec<_>>();
-let y = MutableBuffer::from_trusted_len_iter(x.iter().map(|x| x * 2));
-assert_eq!(y[50], 100);
-# }
-```
-
-Using `from_trusted_len_iter` often causes the compiler to auto-vectorize.
-
-In this context, `MutableBuffer` has an almost identical API to Rust's `Vec`.
-However, contrarily to `Vec`, `Buffer` and `MutableBuffer` only supports
+Contrarily to `Vec`, `Buffer` (and all structs in this crate) only supports
 the following physical types:
 
 * `i8-i128`