src/librustc_incremental/persist/load.rs

   1 //! Code to save/load the dep-graph from files.
   2
   3 use rustc::dep_graph::{PreviousDepGraph, SerializedDepGraph, WorkProduct, WorkProductId};
   4 use rustc::session::Session;
   5 use rustc::ty::query::OnDiskCache;
   6 use rustc::ty::TyCtxt;
   7 use rustc_data_structures::fx::FxHashMap;
   8 use rustc_serialize::opaque::Decoder;
   9 use rustc_serialize::Decodable as RustcDecodable;
  10 use std::path::Path;
  11
  12 use super::data::*;
  13 use super::file_format;
  14 use super::fs::*;
  15 use super::work_product;
  16
  17 pub fn dep_graph_tcx_init(tcx: TyCtxt<'_>) {
  18     if !tcx.dep_graph.is_fully_enabled() {
  19         return;
  20     }
  21
  22     tcx.allocate_metadata_dep_nodes();
  23 }
  24
  25 type WorkProductMap = FxHashMap<WorkProductId, WorkProduct>;
  26
  27 pub enum LoadResult<T> {
  28     Ok { data: T },
  29     DataOutOfDate,
  30     Error { message: String },
  31 }
  32
  33 impl LoadResult<(PreviousDepGraph, WorkProductMap)> {
  34     pub fn open(self, sess: &Session) -> (PreviousDepGraph, WorkProductMap) {
  35         match self {
  36             LoadResult::Error { message } => {
  37                 sess.warn(&message);
  38                 Default::default()
  39             }
  40             LoadResult::DataOutOfDate => {
  41                 if let Err(err) = delete_all_session_dir_contents(sess) {
  42                     sess.err(&format!(
  43                         "Failed to delete invalidated or incompatible \
  44                                       incremental compilation session directory contents `{}`: {}.",
  45                         dep_graph_path(sess).display(),
  46                         err
  47                     ));
  48                 }
  49                 Default::default()
  50             }
  51             LoadResult::Ok { data } => data,
  52         }
  53     }
  54 }
  55
  56 fn load_data(report_incremental_info: bool, path: &Path) -> LoadResult<(Vec<u8>, usize)> {
  57     match file_format::read_file(report_incremental_info, path) {
  58         Ok(Some(data_and_pos)) => LoadResult::Ok { data: data_and_pos },
  59         Ok(None) => {
  60             // The file either didn't exist or was produced by an incompatible
  61             // compiler version. Neither is an error.
  62             LoadResult::DataOutOfDate
  63         }
  64         Err(err) => LoadResult::Error {
  65             message: format!("could not load dep-graph from `{}`: {}", path.display(), err),
  66         },
  67     }
  68 }
  69
  70 fn delete_dirty_work_product(sess: &Session, swp: SerializedWorkProduct) {
  71     debug!("delete_dirty_work_product({:?})", swp);
  72     work_product::delete_workproduct_files(sess, &swp.work_product);
  73 }
  74
  75 /// Either a result that has already be computed or a
  76 /// handle that will let us wait until it is computed
  77 /// by a background thread.
  78 pub enum MaybeAsync<T> {
  79     Sync(T),
  80     Async(std::thread::JoinHandle<T>),
  81 }
  82 impl<T> MaybeAsync<T> {
  83     pub fn open(self) -> std::thread::Result<T> {
  84         match self {
  85             MaybeAsync::Sync(result) => Ok(result),
  86             MaybeAsync::Async(handle) => handle.join(),
  87         }
  88     }
  89 }
  90
  91 pub type DepGraphFuture = MaybeAsync<LoadResult<(PreviousDepGraph, WorkProductMap)>>;
  92
  93 /// Launch a thread and load the dependency graph in the background.
  94 pub fn load_dep_graph(sess: &Session) -> DepGraphFuture {
  95     // Since `sess` isn't `Sync`, we perform all accesses to `sess`
  96     // before we fire the background thread.
  97
  98     let prof = sess.prof.clone();
  99
 100     if sess.opts.incremental.is_none() {
 101         // No incremental compilation.
 102         return MaybeAsync::Sync(LoadResult::Ok { data: Default::default() });
 103     }
 104
 105     // Calling `sess.incr_comp_session_dir()` will panic if `sess.opts.incremental.is_none()`.
 106     // Fortunately, we just checked that this isn't the case.
 107     let path = dep_graph_path_from(&sess.incr_comp_session_dir());
 108     let report_incremental_info = sess.opts.debugging_opts.incremental_info;
 109     let expected_hash = sess.opts.dep_tracking_hash();
 110
 111     let mut prev_work_products = FxHashMap::default();
 112
 113     // If we are only building with -Zquery-dep-graph but without an actual
 114     // incr. comp. session directory, we skip this. Otherwise we'd fail
 115     // when trying to load work products.
 116     if sess.incr_comp_session_dir_opt().is_some() {
 117         let work_products_path = work_products_path(sess);
 118         let load_result = load_data(report_incremental_info, &work_products_path);
 119
 120         if let LoadResult::Ok { data: (work_products_data, start_pos) } = load_result {
 121             // Decode the list of work_products
 122             let mut work_product_decoder = Decoder::new(&work_products_data[..], start_pos);
 123             let work_products: Vec<SerializedWorkProduct> =
 124                 RustcDecodable::decode(&mut work_product_decoder).unwrap_or_else(|e| {
 125                     let msg = format!(
 126                         "Error decoding `work-products` from incremental \
 127                                     compilation session directory: {}",
 128                         e
 129                     );
 130                     sess.fatal(&msg[..])
 131                 });
 132
 133             for swp in work_products {
 134                 let mut all_files_exist = true;
 135                 for &(_, ref file_name) in swp.work_product.saved_files.iter() {
 136                     let path = in_incr_comp_dir_sess(sess, file_name);
 137                     if !path.exists() {
 138                         all_files_exist = false;
 139
 140                         if sess.opts.debugging_opts.incremental_info {
 141                             eprintln!(
 142                                 "incremental: could not find file for work \
 143                                     product: {}",
 144                                 path.display()
 145                             );
 146                         }
 147                     }
 148                 }
 149
 150                 if all_files_exist {
 151                     debug!("reconcile_work_products: all files for {:?} exist", swp);
 152                     prev_work_products.insert(swp.id, swp.work_product);
 153                 } else {
 154                     debug!("reconcile_work_products: some file for {:?} does not exist", swp);
 155                     delete_dirty_work_product(sess, swp);
 156                 }
 157             }
 158         }
 159     }
 160
 161     MaybeAsync::Async(std::thread::spawn(move || {
 162         let _prof_timer = prof.generic_pass("background load prev dep-graph");
 163
 164         match load_data(report_incremental_info, &path) {
 165             LoadResult::DataOutOfDate => LoadResult::DataOutOfDate,
 166             LoadResult::Error { message } => LoadResult::Error { message },
 167             LoadResult::Ok { data: (bytes, start_pos) } => {
 168                 let mut decoder = Decoder::new(&bytes, start_pos);
 169                 let prev_commandline_args_hash = u64::decode(&mut decoder)
 170                     .expect("Error reading commandline arg hash from cached dep-graph");
 171
 172                 if prev_commandline_args_hash != expected_hash {
 173                     if report_incremental_info {
 174                         println!(
 175                             "[incremental] completely ignoring cache because of \
 176                                     differing commandline arguments"
 177                         );
 178                     }
 179                     // We can't reuse the cache, purge it.
 180                     debug!("load_dep_graph_new: differing commandline arg hashes");
 181
 182                     // No need to do any further work
 183                     return LoadResult::DataOutOfDate;
 184                 }
 185
 186                 let dep_graph = SerializedDepGraph::decode(&mut decoder)
 187                     .expect("Error reading cached dep-graph");
 188
 189                 LoadResult::Ok { data: (PreviousDepGraph::new(dep_graph), prev_work_products) }
 190             }
 191         }
 192     }))
 193 }
 194
 195 pub fn load_query_result_cache(sess: &Session) -> OnDiskCache<'_> {
 196     if sess.opts.incremental.is_none() || !sess.opts.debugging_opts.incremental_queries {
 197         return OnDiskCache::new_empty(sess.source_map());
 198     }
 199
 200     let _prof_timer = sess.prof.generic_activity("incr_comp_load_query_result_cache");
 201
 202     match load_data(sess.opts.debugging_opts.incremental_info, &query_cache_path(sess)) {
 203         LoadResult::Ok { data: (bytes, start_pos) } => OnDiskCache::new(sess, bytes, start_pos),
 204         _ => OnDiskCache::new_empty(sess.source_map()),
 205     }
 206 }