@pool now has an optional reserve parameter, some minor changes to the temp_allocator API

lib/std/core/allocators/temp_allocator.c3

@@ -35,6 +35,9 @@ struct TempAllocator (Allocator)
 	TempAllocatorPage* last_page;
 	TempAllocator* derived;
 	bool allocated;
+	usz reserve_size;
+	usz realloc_size;
+	usz min_size;
 	usz used;
 	usz capacity;
 	usz original_capacity;
@@ -62,15 +65,20 @@ macro usz TempAllocatorPage.pagesize(&self) => self.size & ~PAGE_IS_ALIGNED;
 macro bool TempAllocatorPage.is_aligned(&self) => self.size & PAGE_IS_ALIGNED == PAGE_IS_ALIGNED;
 
 <*
- @require size >= 16
+ @require size >= 64
+ @require realloc_size >= 64
  @require allocator.type != TempAllocator.typeid : "You may not create a temp allocator with a TempAllocator as the backing allocator."
+ @require min_size > TempAllocator.sizeof + 64 : "Min size must meaningfully hold the data + some bytes"
 *>
-fn TempAllocator*? new_temp_allocator(Allocator allocator, usz size)
+fn TempAllocator*? new_temp_allocator(Allocator allocator, usz size, usz reserve = temp_allocator_reserve_size, usz min_size = temp_allocator_min_size, usz realloc_size = temp_allocator_realloc_size)
 {
 	TempAllocator* temp = allocator::alloc_with_padding(allocator, TempAllocator, size)!;
 	temp.last_page = null;
 	temp.backing_allocator = allocator;
 	temp.used = 0;
+	temp.min_size = min_size;
+	temp.realloc_size = realloc_size;
+	temp.reserve_size = reserve;
 	temp.allocated = true;
 	temp.derived = null;
 	temp.original_capacity = temp.capacity = size;
@@ -78,19 +86,18 @@ fn TempAllocator*? new_temp_allocator(Allocator allocator, usz size)
 }
 <*
  @require !self.derived
- @require min_size > TempAllocator.sizeof + 64 : "Min size must meaningfully hold the data + some bytes"
- @require mult > 0 : "The multiple can never be zero"
 *>
-fn TempAllocator*? TempAllocator.derive_allocator(&self, usz min_size, usz buffer, usz mult)
+fn TempAllocator*? TempAllocator.derive_allocator(&self, usz reserve = 0)
 {
+	if (!reserve) reserve = self.reserve_size;
 	usz remaining = self.capacity - self.used;
 	void* mem @noinit;
 	usz size @noinit;
-	if (min_size + buffer > remaining)
+	if (self.min_size + reserve > remaining)
 	{
-		return self.derived = new_temp_allocator(self.backing_allocator, min_size * mult)!;
+		return self.derived = new_temp_allocator(self.backing_allocator, self.realloc_size, self.reserve_size, self.min_size, self.realloc_size)!;
 	}
-	usz start = mem::aligned_offset(self.used + buffer, mem::DEFAULT_MEM_ALIGNMENT);
+	usz start = mem::aligned_offset(self.used + reserve, mem::DEFAULT_MEM_ALIGNMENT);
 	void* ptr = &self.data[start];
 	TempAllocator* temp = (TempAllocator*)ptr;
 	$if env::ADDRESS_SANITIZER:
@@ -99,6 +106,9 @@ fn TempAllocator*? TempAllocator.derive_allocator(&self, usz min_size, usz buffe
 	temp.last_page = null;
     temp.backing_allocator = self.backing_allocator;
     temp.used = 0;
+    temp.min_size = self.min_size;
+    temp.reserve_size = self.reserve_size;
+    temp.realloc_size = self.realloc_size;
     temp.allocated = false;
     temp.derived = null;
     temp.original_capacity = temp.capacity = self.capacity - start - TempAllocator.sizeof;

lib/std/core/mem.c3

@@ -576,11 +576,20 @@ fn void temp_pop(PoolState old_state)
 	allocator::pop_pool(old_state) @inline;
 }
 
-macro void @pool_init(Allocator allocator, usz pool_size, usz buffer_size; @body) @builtin
+<*
+ @require pool_size >= 64
+ @require realloc_size >= 64
+ @require allocator.type != TempAllocator.typeid : "You may not create a temp allocator with a TempAllocator as the backing allocator."
+ @require min_size > TempAllocator.sizeof + 64 : "Min size must meaningfully hold the data + some bytes"
+*>
+macro void @pool_init(Allocator allocator, usz pool_size,
+	usz reserve_size = allocator::temp_allocator_reserve_size,
+	usz min_size = allocator::temp_allocator_min_size,
+	usz realloc_size = allocator::temp_allocator_realloc_size; @body) @builtin
 {
 	Allocator current = allocator::current_temp;
 	TempAllocator* top = allocator::top_temp;
-	allocator::create_temp_allocator(allocator, pool_size, buffer_size);
+	allocator::create_temp_allocator(allocator, pool_size, reserve_size, min_size, realloc_size);
 	defer
 	{
 		allocator::destroy_temp_allocators();
@@ -589,9 +598,19 @@ macro void @pool_init(Allocator allocator, usz pool_size, usz buffer_size; @body
 	}
 	@body();
 }
-macro void @pool(;@body) @builtin
+
+<*
+ Create a new temporary allocator.
+
+ The `reserve` parameter allows you to determine how many bytes should be reserved for
+ allocations on the current temporary allocator, if allocations are made inside of the pool scope.
+ It is made available for optimization, and can usually be ignored.
+
+ @param reserve : "The amount of bytes to reserve for out-of-order allocations, 0 gives the default."
+*>
+macro void @pool(usz reserve = 0; @body) @builtin
 {
-	PoolState state = allocator::push_pool() @inline;
+	PoolState state = allocator::push_pool(reserve) @inline;
 	defer
 	{
 		allocator::pop_pool(state) @inline;

lib/std/core/mem_allocator.c3

@@ -407,13 +407,13 @@ tlocal TempAllocator* top_temp;
 tlocal bool auto_create_temp = false;
 
 usz temp_allocator_min_size = temp_allocator_default_min_size();
-usz temp_allocator_buffer_size = temp_allocator_default_buffer_size();
-usz temp_allocator_new_mult = 4;
+usz temp_allocator_reserve_size = temp_allocator_default_reserve_size();
+usz temp_allocator_realloc_size = temp_allocator_default_min_size() * 4;
 
-fn PoolState push_pool()
+fn PoolState push_pool(usz reserve = 0)
 {
 	Allocator old = top_temp ? current_temp : create_temp_allocator_on_demand();
-	current_temp = ((TempAllocator*)old).derive_allocator(temp_allocator_min_size, temp_allocator_buffer_size, temp_allocator_new_mult)!!;
+	current_temp = ((TempAllocator*)old).derive_allocator(reserve)!!;
 	return (PoolState)old.ptr;
 }
 
@@ -453,7 +453,7 @@ macro usz temp_allocator_default_min_size() @local
 	$endswitch
 }
 
-macro usz temp_allocator_default_buffer_size() @local
+macro usz temp_allocator_default_reserve_size() @local
 {
 	$switch env::MEMORY_ENV:
 		$case NORMAL: return 1024;
@@ -475,14 +475,15 @@ fn Allocator create_temp_allocator_on_demand() @private
 	    auto_create_temp = true;
 	    abort("Use '@pool_init()' to enable the temp allocator on a new thread. A temp allocator is only implicitly created on the main thread.");
 	}
-	return create_temp_allocator(temp_base_allocator, temp_allocator_size());
+	return create_temp_allocator(temp_base_allocator, temp_allocator_size(), temp_allocator_reserve_size, temp_allocator_min_size, temp_allocator_realloc_size);
 }
+
 <*
  @require !top_temp : "This should never be called when temp already exists"
 *>
-fn Allocator create_temp_allocator(Allocator allocator, usz size, usz buffer = temp_allocator_default_buffer_size()) @private
+fn Allocator create_temp_allocator(Allocator allocator, usz size, usz reserve, usz min_size, usz realloc_size) @private
 {
-	return current_temp = top_temp = allocator::new_temp_allocator(allocator, size)!!;
+	return current_temp = top_temp = allocator::new_temp_allocator(allocator, size, reserve, min_size, realloc_size)!!;
 }
 
 macro Allocator temp()