Add reserved_bytes method for Allocator (#266)

* Change total_reserved_bytes to total_capacity_bytes in AllocatorReport

The use of "reserved" may be confused with the concept of reserved
memory in Dx12. Capacity is in line with the similar concept from (e.g.)
std::vec::Vec.

* Add capacity method for Allocator

This fills the use case where one needs the total capacity given by the
sum of sizes of all device-allocated memory blocks, but compiling a
complete report (in particular due to the calls to report_allocations
from the SubAllocator) would be too costly.

src/allocator/mod.rs

@@ -61,8 +61,8 @@ pub struct AllocatorReport {
     pub blocks: Vec<MemoryBlockReport>,
     /// Sum of the memory used by all allocations, in bytes.
     pub total_allocated_bytes: u64,
-    /// Sum of the memory reserved by all memory blocks including unallocated regions, in bytes.
-    pub total_reserved_bytes: u64,
+    /// Sum of the memory capacity of all memory blocks including unallocated regions, in bytes.
+    pub total_capacity_bytes: u64,
 }
 
 impl fmt::Debug for AllocationReport {
@@ -90,7 +90,7 @@ impl fmt::Debug for AllocatorReport {
                 &std::format_args!(
                     "{} / {}",
                     fmt_bytes(self.total_allocated_bytes),
-                    fmt_bytes(self.total_reserved_bytes)
+                    fmt_bytes(self.total_capacity_bytes)
                 ),
             )
             .field("blocks", &self.blocks.len())

src/d3d12/mod.rs

@@ -1126,11 +1126,11 @@ impl Allocator {
     pub fn generate_report(&self) -> AllocatorReport {
         let mut allocations = vec![];
         let mut blocks = vec![];
-        let mut total_reserved_bytes = 0;
+        let mut total_capacity_bytes = 0;
 
         for memory_type in &self.memory_types {
             for block in memory_type.memory_blocks.iter().flatten() {
-                total_reserved_bytes += block.size;
+                total_capacity_bytes += block.size;
                 let first_allocation = allocations.len();
                 allocations.extend(block.sub_allocator.report_allocations());
                 blocks.push(MemoryBlockReport {
@@ -1146,9 +1146,22 @@ impl Allocator {
             allocations,
             blocks,
             total_allocated_bytes,
-            total_reserved_bytes,
+            total_capacity_bytes,
         }
     }
+
+    /// Current total capacity of memory blocks allocated on the device, in bytes
+    pub fn capacity(&self) -> u64 {
+        let mut total_capacity_bytes = 0;
+
+        for memory_type in &self.memory_types {
+            for block in memory_type.memory_blocks.iter().flatten() {
+                total_capacity_bytes += block.size;
+            }
+        }
+
+        total_capacity_bytes
+    }
 }
 
 impl fmt::Debug for Allocator {

src/metal/mod.rs

@@ -518,11 +518,11 @@ impl Allocator {
     pub fn generate_report(&self) -> AllocatorReport {
         let mut allocations = vec![];
         let mut blocks = vec![];
-        let mut total_reserved_bytes = 0;
+        let mut total_capacity_bytes = 0;
 
         for memory_type in &self.memory_types {
             for block in memory_type.memory_blocks.iter().flatten() {
-                total_reserved_bytes += block.size;
+                total_capacity_bytes += block.size;
                 let first_allocation = allocations.len();
                 allocations.extend(block.sub_allocator.report_allocations());
                 blocks.push(MemoryBlockReport {
@@ -538,7 +538,20 @@ impl Allocator {
             allocations,
             blocks,
             total_allocated_bytes,
-            total_reserved_bytes,
+            total_capacity_bytes,
         }
     }
+
+    /// Current total capacity of memory blocks allocated on the device, in bytes
+    pub fn capacity(&self) -> u64 {
+        let mut total_capacity_bytes = 0;
+
+        for memory_type in &self.memory_types {
+            for block in memory_type.memory_blocks.iter().flatten() {
+                total_capacity_bytes += block.size;
+            }
+        }
+
+        total_capacity_bytes
+    }
 }

src/vulkan/mod.rs

@@ -934,11 +934,11 @@ impl Allocator {
     pub fn generate_report(&self) -> AllocatorReport {
         let mut allocations = vec![];
         let mut blocks = vec![];
-        let mut total_reserved_bytes = 0;
+        let mut total_capacity_bytes = 0;
 
         for memory_type in &self.memory_types {
             for block in memory_type.memory_blocks.iter().flatten() {
-                total_reserved_bytes += block.size;
+                total_capacity_bytes += block.size;
                 let first_allocation = allocations.len();
                 allocations.extend(block.sub_allocator.report_allocations());
                 blocks.push(MemoryBlockReport {
@@ -954,9 +954,22 @@ impl Allocator {
             allocations,
             blocks,
             total_allocated_bytes,
-            total_reserved_bytes,
+            total_capacity_bytes,
         }
     }
+
+    /// Current total capacity of memory blocks allocated on the device, in bytes
+    pub fn capacity(&self) -> u64 {
+        let mut total_capacity_bytes = 0;
+
+        for memory_type in &self.memory_types {
+            for block in memory_type.memory_blocks.iter().flatten() {
+                total_capacity_bytes += block.size;
+            }
+        }
+
+        total_capacity_bytes
+    }
 }
 
 impl Drop for Allocator {