Renaming and a new macro

README.md

@@ -8,15 +8,53 @@
 
 
 ---
-# The Quick And Dirty Allocation Profiling Tool
+# QADAPT - `debug_assert!` for your memory
 
-This allocator is a helper for writing high-performance code that is allocation/drop free;
-for functions annotated with `#[allocate_panic]`, QADAPT will detect when allocations/drops
-happen during their execution (and execution of any functions they call) and throw a
-thread panic if this occurs. QADAPT-related code is *stripped out during release builds*,
-so no worries about random allocations crashing in production.
+This allocator is a helper for writing high-performance code that is memory-sensitive;
+a thread panic will be triggered if a function annotated with `#[no_alloc]`,
+or code inside an `assert_no_alloc!` macro interacts with the allocator in any way.
+Wanton allocations and unforeseen drops no more - this library lets you focus on
+writing code without worrying if Rust properly managed to inline the variable into the stack.
 
-Currently this crate is Nightly-only, but will work once `const fn` is in Stable.
+Now, an allocator blowing up in production is a scary thought; that's why QADAPT
+is designed to strip its own code out whenever you're running with a release build.
+Just like the [`debug_assert!` macro](https://doc.rust-lang.org/std/macro.debug_assert.html)
+in Rust's standard library, it's safe to use without worrying about a unforeseen
+circumstance causing your application to crash.
 
-Please also take a look at [qadapt-macro](https://github.com/bspeice/qadapt/tree/master/qadapt-macro)
-for some helper macros to make working with QADAPT a bit easier.
+# Usage
+
+Actually making use of QADAPT is straight-forward. To set up the allocator,
+place the following snippet in either your program binaries (main.rs) or tests:
+
+```rust,ignore
+use qadapt::QADAPT;
+
+#[global_allocator]
+static Q: QADAPT = QADAPT;
+```
+
+After that, there are two ways of telling QADAPT that it should trigger a panic:
+
+1. Annotate functions with the `#[no_alloc]` proc macro:
+```rust,no_run
+use qadapt::no_alloc;
+
+#[no_alloc]
+fn do_math() -> u8 {
+2 + 2
+}
+```
+
+2. Evaluate expressions with the `assert_no_alloc!` macro
+```rust,no_run
+use qadapt::assert_no_alloc;
+
+fn do_work() {
+// This code is allowed to trigger an allocation
+let b = Box::new(8);
+
+// This code would panic if an allocation occurred inside it
+let x = assert_no_alloc!(*b + 2);
+assert_eq!(x, 10);
+}

examples/release_mode.rs

@@ -1,10 +1,10 @@
-use qadapt::allocate_panic;
+use qadapt::no_alloc;
 use qadapt::QADAPT;
 
 #[global_allocator]
 static Q: QADAPT = QADAPT;
 
-#[allocate_panic]
+#[no_alloc]
 fn does_allocate() -> Box<u8> {
     Box::new(0)
 }

examples/setup_warning.rs

@@ -1,20 +0,0 @@
-use env_logger;
-
-use qadapt::allocate_panic;
-
-// Note that we're missing the `#[global_allocator]` attribute
-
-#[allocate_panic]
-fn does_allocate() -> Box<u8> {
-    Box::new(0)
-}
-
-fn main() {
-    // This code will warn that QADAPT isn't being used, but won't trigger a panic.
-    // Run with `RUST_LOG=warn cargo run --example setup_warning`
-    env_logger::init();
-    does_allocate();
-
-    // The warning will only trigger once though
-    does_allocate();
-}

qadapt-macro/src/lib.rs

@@ -155,7 +155,7 @@ fn escape_return(ts: TokenStream) -> TokenStream {
 /// separate thread, or defers allocations via closure/Future, those results
 /// will not trigger an error.
 #[proc_macro_attribute]
-pub fn allocate_panic(_attr: TokenStream, item: TokenStream) -> TokenStream {
+pub fn no_alloc(_attr: TokenStream, item: TokenStream) -> TokenStream {
     let mut protected_fn: Vec<TokenTree> = Vec::new();
     let mut item_iter = item.into_iter();
 

src/lib.rs

@@ -1,15 +1,53 @@
-//! # The Quick And Dirty Allocation Profiling Tool
+//! # QADAPT - `debug_assert!` for your memory
 //!
-//! This allocator is a helper for writing high-performance code that is allocation/drop free;
-//! for functions annotated with `#[allocate_panic]`, QADAPT will detect when allocations/drops
-//! happen during their execution (and execution of any functions they call) and throw a
-//! thread panic if this occurs. QADAPT-related code is *stripped out during release builds*,
-//! so no worries about random allocations crashing in production.
-//!
-//! Currently this crate is Nightly-only, but will work once `const fn` is in Stable.
-//!
-//! Please also take a look at [qadapt-macro](https://github.com/bspeice/qadapt/tree/master/qadapt-macro)
-//! for some helper macros to make working with QADAPT a bit easier.
+//! This allocator is a helper for writing high-performance code that is memory-sensitive;
+//! a thread panic will be triggered if a function annotated with `#[no_alloc]`,
+//! or code inside an `assert_no_alloc!` macro interacts with the allocator in any way.
+//! Wanton allocations and unforeseen drops no more - this library lets you focus on
+//! writing code without worrying if Rust properly managed to inline the variable into the stack.
+//! 
+//! Now, an allocator blowing up in production is a scary thought; that's why QADAPT
+//! is designed to strip its own code out whenever you're running with a release build.
+//! Just like the [`debug_assert!` macro](https://doc.rust-lang.org/std/macro.debug_assert.html)
+//! in Rust's standard library, it's safe to use without worrying about a unforeseen
+//! circumstance causing your application to crash.
+//! 
+//! # Usage
+//! 
+//! Actually making use of QADAPT is straight-forward. To set up the allocator,
+//! place the following snippet in either your program binaries (main.rs) or tests:
+//! 
+//! ```rust,ignore
+//! use qadapt::QADAPT;
+//! 
+//! #[global_allocator]
+//! static Q: QADAPT = QADAPT;
+//! ```
+//! 
+//! After that, there are two ways of telling QADAPT that it should trigger a panic:
+//! 
+//! 1. Annotate functions with the `#[no_alloc]` proc macro:
+//! ```rust,no_run
+//! use qadapt::no_alloc;
+//! 
+//! #[no_alloc]
+//! fn do_math() -> u8 {
+//!     2 + 2
+//! }
+//! ```
+//! 
+//! 2. Evaluate expressions with the `assert_no_alloc!` macro
+//! ```rust,no_run
+//! use qadapt::assert_no_alloc;
+//! 
+//! fn do_work() {
+//!     // This code is allowed to trigger an allocation
+//!     let b = Box::new(8);
+//!     
+//!     // This code would panic if an allocation occurred inside it
+//!     let x = assert_no_alloc!(*b + 2);
+//!     assert_eq!(x, 10);
+//! }
 #![deny(missing_docs)]
 
 use log::warn;
@@ -45,8 +83,7 @@ pub fn enter_protected() {
         }
 
         if !*IS_ACTIVE.read() {
-            *IS_ACTIVE.write() = true;
-            warn!("QADAPT not initialized when using allocation guards; please verify `#[global_allocator]` is set!");
+            panic!("QADAPT not initialized when using allocation guards; please verify `#[global_allocator]` is set!");
         }
 
         PROTECTION_LEVEL
@@ -80,17 +117,30 @@ pub fn exit_protected() {
     }
 }
 
+/// Get the result of an expression, guaranteeing that no allocations occur
+/// during its evaluation.
+/// 
+/// **Warning**: Unexpected behavior may occur when using the `return` keyword.
+/// Because the macro cleanup logic will not be run, QADAPT may trigger a panic
+/// in code that was not specifically intended to be allocation-free.
+#[macro_export]
+macro_rules! assert_no_alloc {
+    ($e:expr) => {{
+        ::qadapt::enter_protected();
+        let e = { $e };
+        ::qadapt::exit_protected();
+        e
+    }};
+}
+
 static IS_ACTIVE: RwLock<bool> = RwLock::new(false);
 static INTERNAL_ALLOCATION: RwLock<usize> = RwLock::new(usize::max_value());
 
 /// Get the current "protection level" in QADAPT: calls to enter_protected() - exit_protected()
 pub fn protection_level() -> usize {
-    #[cfg(debug_assertions)]
-    {
+    if cfg!(debug_assertions) {
         PROTECTION_LEVEL.try_with(|v| *v.read()).unwrap_or(0)
-    }
-    #[cfg(not(debug_assertions))]
-    {
+    } else {
         0
     }
 }
@@ -131,7 +181,7 @@ unsafe impl GlobalAlloc for QADAPT {
         }
 
         // Because accessing PROTECTION_LEVEL has the potential to trigger an allocation,
-        // we need to spin until we can claim the INTERNAL_ALLOCATION lock for our thread.
+        // we need to acquire the INTERNAL_ALLOCATION lock for our thread.
         claim_internal_alloc();
         let protection_level: Result<usize, ()> =
             PROTECTION_LEVEL.try_with(|v| *v.read()).or(Ok(0));
@@ -167,7 +217,7 @@ unsafe impl GlobalAlloc for QADAPT {
         free(ptr as *mut c_void);
         match protection_level {
             Ok(v) if v > 0 => {
-                // Tripped a bad dealloc, but make sure further memory access during unwind
+                // Tripped a bad drop, but make sure further memory access during unwind
                 // doesn't have issues
                 PROTECTION_LEVEL.with(|v| *v.write() = 0);
                 panic!(

tests/assert_macro.rs

@@ -0,0 +1,26 @@
+use qadapt::assert_no_alloc;
+use qadapt::QADAPT;
+
+#[global_allocator]
+static Q: QADAPT = QADAPT;
+
+#[test]
+fn math() {
+    let x = assert_no_alloc!(2 + 2);
+    assert_eq!(x, 4);
+}
+
+fn early_return() -> usize {
+    assert_no_alloc!(return 8)
+}
+
+fn into_box() -> Box<usize> {
+    Box::new(early_return())
+}
+
+#[test]
+#[should_panic]
+fn early_return_boxing() {
+    into_box();
+}
+

tests/proc_macro.rs

@@ -1,12 +1,12 @@
 use std::io;
 
-use qadapt::allocate_panic;
+use qadapt::no_alloc;
 use qadapt::QADAPT;
 
 #[global_allocator]
 static Q: QADAPT = QADAPT;
 
-#[allocate_panic]
+#[no_alloc]
 fn no_allocate() {
     let _v: Vec<()> = Vec::with_capacity(0);
 }
@@ -16,7 +16,7 @@ fn macro_no_allocate() {
     no_allocate();
 }
 
-#[allocate_panic]
+#[no_alloc]
 fn allocates() {
     assert_eq!(::qadapt::protection_level(), 1);
     // Without boxing, release profile can actually optimize out the allocation
@@ -30,7 +30,7 @@ fn macro_allocates() {
     allocates();
 }
 
-#[allocate_panic]
+#[no_alloc]
 fn no_allocate_ret() -> bool {
     return true;
 }
@@ -40,7 +40,7 @@ fn macro_return() {
     assert!(no_allocate_ret());
 }
 
-#[allocate_panic]
+#[no_alloc]
 fn no_allocate_implicit_ret() -> bool {
     true
 }
@@ -50,7 +50,7 @@ fn macro_implicit_return() {
     assert!(no_allocate_implicit_ret());
 }
 
-#[allocate_panic]
+#[no_alloc]
 fn no_allocate_arg(b: bool) -> bool {
     b
 }
@@ -61,7 +61,7 @@ fn macro_allocate_arg() {
     no_allocate_arg(false);
 }
 
-#[allocate_panic]
+#[no_alloc]
 fn no_allocate_args(_b: bool, _u: usize, i: i64) -> i64 {
     i
 }
@@ -72,7 +72,7 @@ fn macro_allocate_args() {
     no_allocate_args(false, 4, -90);
 }
 
-#[allocate_panic]
+#[no_alloc]
 fn return_result(r: Result<usize, io::Error>) -> Result<Result<usize, io::Error>, ()> {
     Ok(r)
 }
@@ -82,7 +82,7 @@ fn macro_return_result() {
     return_result(Ok(16)).unwrap().unwrap();
 }
 
-#[allocate_panic]
+#[no_alloc]
 fn branching_return(a: bool, b: bool, c: bool) -> u8 {
     if a {
         if b {
@@ -131,7 +131,7 @@ fn run_closure(x: impl Fn(bool, bool) -> bool) -> bool {
     x(true, false)
 }
 
-#[allocate_panic]
+#[no_alloc]
 fn example_closure() {
     let c = run_closure(|a: bool, b| return a && b);
     assert!(!c);
@@ -145,7 +145,7 @@ fn macro_closure() {
 }
 
 #[test]
-#[allocate_panic]
+#[no_alloc]
 fn macro_release_safe() {
     #[cfg(debug_assertions)]
     {

tests/unused_panic.rs

@@ -0,0 +1,7 @@
+use qadapt::enter_protected;
+
+#[test]
+#[should_panic]
+fn guard_without_initialization() {
+    enter_protected();
+}