From f9cd55ed59cbecf9da36f8412390e292871c1e86 Mon Sep 17 00:00:00 2001
From: Dzmitry Malyshau <dmalyshau@mozilla.com>
Date: Fri, 19 Oct 2018 10:45:11 -0400
Subject: [PATCH] Share use_xxx implementations in the tracker

---
 wgpu-native/src/command/mod.rs    |  2 -
 wgpu-native/src/command/render.rs |  7 +--
 wgpu-native/src/track.rs          | 76 +++++++++++++++----------------
 3 files changed, 39 insertions(+), 46 deletions(-)

diff --git a/wgpu-native/src/command/mod.rs b/wgpu-native/src/command/mod.rs
index 695a102776..d4dd5658be 100644
--- a/wgpu-native/src/command/mod.rs
+++ b/wgpu-native/src/command/mod.rs
@@ -92,7 +92,6 @@ pub extern "C" fn wgpu_command_buffer_begin_render_pass(
     let device_guard = HUB.devices.lock();
     let device = device_guard.get(cmb.device_id.0);
 
-    let transit_comb = cmb.raw.pop().unwrap();
     let current_comb = device.com_allocator.extend(cmb);
 
     //let render_pass = device.create_render_pass();
@@ -111,7 +110,6 @@ pub extern "C" fn wgpu_command_buffer_begin_render_pass(
         .lock()
         .register(RenderPass::new(
             current_comb,
-            transit_comb,
             command_buffer_id,
         ))
 }
diff --git a/wgpu-native/src/command/render.rs b/wgpu-native/src/command/render.rs
index 4c4dd1b450..2c5892738d 100644
--- a/wgpu-native/src/command/render.rs
+++ b/wgpu-native/src/command/render.rs
@@ -13,7 +13,6 @@ use std::iter;
 
 pub struct RenderPass<B: hal::Backend> {
     raw: B::CommandBuffer,
-    parent: B::CommandBuffer,
     cmb_id: Stored<CommandBufferId>,
     tracker: Tracker,
 }
@@ -21,12 +20,10 @@ pub struct RenderPass<B: hal::Backend> {
 impl<B: hal::Backend> RenderPass<B> {
     pub fn new(
         raw: B::CommandBuffer,
-        parent: B::CommandBuffer,
         cmb_id: CommandBufferId,
     ) -> Self {
         RenderPass {
             raw,
-            parent,
             cmb_id: Stored(cmb_id),
             tracker: Tracker::default(),
         }
@@ -42,13 +39,11 @@ pub extern "C" fn wgpu_render_pass_end_pass(
         .take(pass_id);
     pass.raw.end_render_pass();
 
-    let combs = iter::once(pass.parent)
-        .chain(iter::once(pass.raw));
     HUB.command_buffers
         .lock()
         .get_mut(pass.cmb_id.0)
         .raw
-        .extend(combs);
+        .push(pass.raw);
 
     pass.cmb_id.0
 }
diff --git a/wgpu-native/src/track.rs b/wgpu-native/src/track.rs
index 7f72a1f2e0..d3584bb51e 100644
--- a/wgpu-native/src/track.rs
+++ b/wgpu-native/src/track.rs
@@ -2,7 +2,8 @@ use {Stored, BufferId, TextureId};
 use resource::{BufferUsageFlags, TextureUsageFlags};
 
 use std::collections::hash_map::{Entry, HashMap};
-use std::ops::Range;
+use std::hash::Hash;
+use std::ops::BitOr;
 use std::sync::Mutex;
 
 
@@ -22,33 +23,47 @@ bitflags! {
 }
 
 
+trait GenericUsage {
+    fn is_exclusive(&self) -> bool;
+}
+impl GenericUsage for BufferUsageFlags {
+    fn is_exclusive(&self) -> bool {
+        BufferUsageFlags::WRITE_ALL.intersects(*self)
+    }
+}
+impl GenericUsage for TextureUsageFlags {
+    fn is_exclusive(&self) -> bool {
+        TextureUsageFlags::WRITE_ALL.intersects(*self)
+    }
+}
+
 #[derive(Default)]
 pub struct Tracker {
-    buffers: Mutex<HashMap<Stored<BufferId>, Range<BufferUsageFlags>>>,
-    textures: Mutex<HashMap<Stored<TextureId>, Range<TextureUsageFlags>>>,
+    buffers: Mutex<HashMap<Stored<BufferId>, BufferUsageFlags>>,
+    textures: Mutex<HashMap<Stored<TextureId>, TextureUsageFlags>>,
 }
 
 impl Tracker {
-    pub(crate) fn use_buffer(
-        &self, id: Stored<BufferId>, usage: BufferUsageFlags, permit: UsePermit,
-    ) -> Result<UseAction<BufferUsageFlags>, BufferUsageFlags> {
-        match self.buffers.lock().unwrap().entry(id) {
+    fn use_impl<I, U>(
+        map: &mut HashMap<I, U>, id: I, usage: U, permit: UsePermit
+    ) -> Result<UseAction<U>, U>
+    where
+        I: Hash + Eq,
+        U: Copy + GenericUsage + BitOr<Output = U> + PartialEq,
+    {
+        match map.entry(id) {
             Entry::Vacant(e) => {
-                e.insert(usage .. usage);
+                e.insert(usage);
                 Ok(UseAction::Init)
             }
             Entry::Occupied(mut e) => {
-                let old = e.get().end;
+                let old = *e.get();
                 if usage == old {
                     Ok(UseAction::Keep)
-                } else if permit.contains(UsePermit::EXTEND) &&
-                    !BufferUsageFlags::WRITE_ALL.intersects(old | usage)
-                {
-                    e.get_mut().end |= usage;
-                    Ok(UseAction::Extend { old })
+                } else if permit.contains(UsePermit::EXTEND) && !(old | usage).is_exclusive() {
+                    Ok(UseAction::Extend { old: e.insert(old | usage) })
                 } else if permit.contains(UsePermit::REPLACE) {
-                    e.get_mut().end = usage;
-                    Ok(UseAction::Replace { old })
+                    Ok(UseAction::Replace { old: e.insert(usage) })
                 } else {
                     Err(old)
                 }
@@ -56,30 +71,15 @@ impl Tracker {
         }
     }
 
+    pub(crate) fn use_buffer(
+        &self, id: Stored<BufferId>, usage: BufferUsageFlags, permit: UsePermit,
+    ) -> Result<UseAction<BufferUsageFlags>, BufferUsageFlags> {
+        Self::use_impl(&mut *self.buffers.lock().unwrap(), id, usage, permit)
+    }
+
     pub(crate) fn use_texture(
         &self, id: Stored<TextureId>, usage: TextureUsageFlags, permit: UsePermit,
     ) -> Result<UseAction<TextureUsageFlags>, TextureUsageFlags> {
-        match self.textures.lock().unwrap().entry(id) {
-            Entry::Vacant(e) => {
-                e.insert(usage .. usage);
-                Ok(UseAction::Init)
-            }
-            Entry::Occupied(mut e) => {
-                let old = e.get().end;
-                if usage == old {
-                    Ok(UseAction::Keep)
-                } else if permit.contains(UsePermit::EXTEND) &&
-                    !TextureUsageFlags::WRITE_ALL.intersects(old | usage)
-                {
-                    e.get_mut().end |= usage;
-                    Ok(UseAction::Extend { old })
-                } else if permit.contains(UsePermit::REPLACE) {
-                    e.get_mut().end = usage;
-                    Ok(UseAction::Replace { old })
-                } else {
-                    Err(old)
-                }
-            }
-        }
+        Self::use_impl(&mut *self.textures.lock().unwrap(), id, usage, permit)
     }
 }