Implement better error handling

Fixes #9

Author: wesleywiser

measureme/src/file_serialization_sink.rs

@@ -1,4 +1,5 @@
 use crate::serialization::{Addr, SerializationSink};
+use std::error::Error;
 use std::fs;
 use std::io::{BufWriter, Write};
 use std::path::Path;
@@ -9,16 +10,14 @@ pub struct FileSerializationSink {
 }
 
 impl SerializationSink for FileSerializationSink {
-    fn from_path(path: &Path) -> Self {
-        // TODO: This is very crude error handling.
-        //       https://github.com/rust-lang/measureme/issues/9
-        fs::create_dir_all(path.parent().unwrap()).unwrap();
+    fn from_path(path: &Path) -> Result<Self, Box<dyn Error>> {
+        fs::create_dir_all(path.parent().unwrap())?;
 
-        let file = fs::File::create(path).expect("couldn't open file: {}");
+        let file = fs::File::create(path)?;
 
-        FileSerializationSink {
+        Ok(FileSerializationSink {
             data: Mutex::new((BufWriter::new(file), 0)),
-        }
+        })
     }
 
     #[inline]

measureme/src/mmap_serialization_sink.rs

@@ -1,5 +1,6 @@
 use crate::serialization::{Addr, SerializationSink};
 use memmap::{MmapMut};
+use std::error::Error;
 use std::io::{Write, BufWriter};
 use std::fs::{File};
 use std::path::{Path, PathBuf};
@@ -12,17 +13,17 @@ pub struct MmapSerializationSink {
 }
 
 impl SerializationSink for MmapSerializationSink {
-    fn from_path(path: &Path) -> Self {
+    fn from_path(path: &Path) -> Result<Self, Box<dyn Error>> {
         // Lazily allocate 1 GB :O
         let file_size = 1 << 30;
 
-        let mapped_file = MmapMut::map_anon(file_size).unwrap();
+        let mapped_file = MmapMut::map_anon(file_size)?;
 
-        MmapSerializationSink {
+        Ok(MmapSerializationSink {
             mapped_file,
             current_pos: AtomicUsize::new(0),
             path: path.to_path_buf(),
-        }
+        })
     }
 
     #[inline]

measureme/src/profiler.rs

@@ -1,6 +1,7 @@
 use crate::raw_event::{RawEvent, Timestamp, TimestampKind};
 use crate::serialization::SerializationSink;
 use crate::stringtable::{SerializableString, StringId, StringTableBuilder};
+use std::error::Error;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
 use std::time::Instant;
@@ -28,19 +29,19 @@ pub struct Profiler<S: SerializationSink> {
 }
 
 impl<S: SerializationSink> Profiler<S> {
-    pub fn new(path_stem: &Path) -> Profiler<S> {
+    pub fn new(path_stem: &Path) -> Result<Profiler<S>, Box<dyn Error>> {
         let paths = ProfilerFiles::new(path_stem);
-        let event_sink = Arc::new(S::from_path(&paths.events_file));
+        let event_sink = Arc::new(S::from_path(&paths.events_file)?);
         let string_table = StringTableBuilder::new(
-            Arc::new(S::from_path(&paths.string_data_file)),
-            Arc::new(S::from_path(&paths.string_index_file)),
+            Arc::new(S::from_path(&paths.string_data_file)?),
+            Arc::new(S::from_path(&paths.string_index_file)?),
         );
 
-        Profiler {
+        Ok(Profiler {
             event_sink,
             string_table,
             start_time: Instant::now(),
-        }
+        })
     }
 
     #[inline(always)]

measureme/src/serialization.rs

@@ -1,3 +1,4 @@
+use std::error::Error;
 use std::path::Path;
 
 #[derive(Clone, Copy, Eq, PartialEq, Debug)]
@@ -9,8 +10,8 @@ impl Addr {
     }
 }
 
-pub trait SerializationSink {
-    fn from_path(path: &Path) -> Self;
+pub trait SerializationSink: Sized {
+    fn from_path(path: &Path) -> Result<Self, Box<dyn Error>>;
 
     fn write_atomic<W>(&self, num_bytes: usize, write: W) -> Addr
     where
@@ -39,7 +40,7 @@ pub mod test {
     }
 
     impl SerializationSink for TestSink {
-        fn from_path(_path: &Path) -> Self {
+        fn from_path(_path: &Path) -> Result<Self, Box<dyn Error>> {
             unimplemented!()
         }
 

measureme/src/testing_common.rs

@@ -22,7 +22,7 @@ fn mk_filestem(file_name_stem: &str) -> PathBuf {
 
 // Generate some profiling data. This is the part that would run in rustc.
 fn generate_profiling_data<S: SerializationSink>(filestem: &Path) -> Vec<Event> {
-    let profiler = Arc::new(Profiler::<S>::new(Path::new(filestem)));
+    let profiler = Arc::new(Profiler::<S>::new(Path::new(filestem)).unwrap());
 
     let event_id_reserved = StringId::reserved(42);