src/librustc/dep_graph/graph.rs

   1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use hir::def_id::DefId;
  12 use rustc_data_structures::fnv::FnvHashMap;
  13 use session::config::OutputType;
  14 use std::cell::{Ref, RefCell};
  15 use std::rc::Rc;
  16 use std::sync::Arc;
  17
  18 use super::dep_node::{DepNode, WorkProductId};
  19 use super::query::DepGraphQuery;
  20 use super::raii;
  21 use super::thread::{DepGraphThreadData, DepMessage};
  22
  23 #[derive(Clone)]
  24 pub struct DepGraph {
  25     data: Rc<DepGraphData>
  26 }
  27
  28 struct DepGraphData {
  29     /// We send messages to the thread to let it build up the dep-graph
  30     /// from the current run.
  31     thread: DepGraphThreadData,
  32
  33     /// When we load, there may be `.o` files, cached mir, or other such
  34     /// things available to us. If we find that they are not dirty, we
  35     /// load the path to the file storing those work-products here into
  36     /// this map. We can later look for and extract that data.
  37     previous_work_products: RefCell<FnvHashMap<Arc<WorkProductId>, WorkProduct>>,
  38
  39     /// Work-products that we generate in this run.
  40     work_products: RefCell<FnvHashMap<Arc<WorkProductId>, WorkProduct>>,
  41 }
  42
  43 impl DepGraph {
  44     pub fn new(enabled: bool) -> DepGraph {
  45         DepGraph {
  46             data: Rc::new(DepGraphData {
  47                 thread: DepGraphThreadData::new(enabled),
  48                 previous_work_products: RefCell::new(FnvHashMap()),
  49                 work_products: RefCell::new(FnvHashMap()),
  50             })
  51         }
  52     }
  53
  54     pub fn query(&self) -> DepGraphQuery<DefId> {
  55         self.data.thread.query()
  56     }
  57
  58     pub fn in_ignore<'graph>(&'graph self) -> Option<raii::IgnoreTask<'graph>> {
  59         raii::IgnoreTask::new(&self.data.thread)
  60     }
  61
  62     pub fn in_task<'graph>(&'graph self, key: DepNode<DefId>) -> Option<raii::DepTask<'graph>> {
  63         raii::DepTask::new(&self.data.thread, key)
  64     }
  65
  66     pub fn with_ignore<OP,R>(&self, op: OP) -> R
  67         where OP: FnOnce() -> R
  68     {
  69         let _task = self.in_ignore();
  70         op()
  71     }
  72
  73     pub fn with_task<OP,R>(&self, key: DepNode<DefId>, op: OP) -> R
  74         where OP: FnOnce() -> R
  75     {
  76         let _task = self.in_task(key);
  77         op()
  78     }
  79
  80     pub fn read(&self, v: DepNode<DefId>) {
  81         if self.data.thread.is_enqueue_enabled() {
  82             self.data.thread.enqueue(DepMessage::Read(v));
  83         }
  84     }
  85
  86     pub fn write(&self, v: DepNode<DefId>) {
  87         if self.data.thread.is_enqueue_enabled() {
  88             self.data.thread.enqueue(DepMessage::Write(v));
  89         }
  90     }
  91
  92     /// Indicates that a previous work product exists for `v`. This is
  93     /// invoked during initial start-up based on what nodes are clean
  94     /// (and what files exist in the incr. directory).
  95     pub fn insert_previous_work_product(&self, v: &Arc<WorkProductId>, data: WorkProduct) {
  96         debug!("insert_previous_work_product({:?}, {:?})", v, data);
  97         self.data.previous_work_products.borrow_mut()
  98                                         .insert(v.clone(), data);
  99     }
 100
 101     /// Indicates that we created the given work-product in this run
 102     /// for `v`. This record will be preserved and loaded in the next
 103     /// run.
 104     pub fn insert_work_product(&self, v: &Arc<WorkProductId>, data: WorkProduct) {
 105         debug!("insert_work_product({:?}, {:?})", v, data);
 106         self.data.work_products.borrow_mut()
 107                                .insert(v.clone(), data);
 108     }
 109
 110     /// Check whether a previous work product exists for `v` and, if
 111     /// so, return the path that leads to it. Used to skip doing work.
 112     pub fn previous_work_product(&self, v: &Arc<WorkProductId>) -> Option<WorkProduct> {
 113         self.data.previous_work_products.borrow()
 114                                         .get(v)
 115                                         .cloned()
 116     }
 117
 118     /// Access the map of work-products created during this run. Only
 119     /// used during saving of the dep-graph.
 120     pub fn work_products(&self) -> Ref<FnvHashMap<Arc<WorkProductId>, WorkProduct>> {
 121         self.data.work_products.borrow()
 122     }
 123 }
 124
 125 /// A "work product" is an intermediate result that we save into the
 126 /// incremental directory for later re-use. The primary example are
 127 /// the object files that we save for each partition at code
 128 /// generation time.
 129 ///
 130 /// Each work product is associated with a dep-node, representing the
 131 /// process that produced the work-product. If that dep-node is found
 132 /// to be dirty when we load up, then we will delete the work-product
 133 /// at load time. If the work-product is found to be clean, then we
 134 /// will keep a record in the `previous_work_products` list.
 135 ///
 136 /// In addition, work products have an associated hash. This hash is
 137 /// an extra hash that can be used to decide if the work-product from
 138 /// a previous compilation can be re-used (in addition to the dirty
 139 /// edges check).
 140 ///
 141 /// As the primary example, consider the object files we generate for
 142 /// each partition. In the first run, we create partitions based on
 143 /// the symbols that need to be compiled. For each partition P, we
 144 /// hash the symbols in P and create a `WorkProduct` record associated
 145 /// with `DepNode::TransPartition(P)`; the hash is the set of symbols
 146 /// in P.
 147 ///
 148 /// The next time we compile, if the `DepNode::TransPartition(P)` is
 149 /// judged to be clean (which means none of the things we read to
 150 /// generate the partition were found to be dirty), it will be loaded
 151 /// into previous work products. We will then regenerate the set of
 152 /// symbols in the partition P and hash them (note that new symbols
 153 /// may be added -- for example, new monomorphizations -- even if
 154 /// nothing in P changed!). We will compare that hash against the
 155 /// previous hash. If it matches up, we can reuse the object file.
 156 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
 157 pub struct WorkProduct {
 158     /// Extra hash used to decide if work-product is still suitable;
 159     /// note that this is *not* a hash of the work-product itself.
 160     /// See documentation on `WorkProduct` type for an example.
 161     pub input_hash: u64,
 162
 163     /// Saved files associated with this CGU
 164     pub saved_files: Vec<(OutputType, String)>,
 165 }