From ad74518a9dd49832a3bb1e81ec0786be37dc52c7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?F=C3=A9lix=20Saparelli?= <felix@passcod.name>
Date: Tue, 2 Jul 2019 03:46:08 +1200
Subject: [PATCH] refactor(index): idiomatise various iterators (#1)

* chore(index): idiomatise variously

* chore(index): exploit hashset to dedupe entries

* chore(index): format
---
 src/index.rs | 137 ++++++++++++++++++++++++++-------------------------
 src/lib.rs   |   2 +-
 2 files changed, 72 insertions(+), 67 deletions(-)

diff --git a/src/index.rs b/src/index.rs
index f6e8a34..38cdf52 100644
--- a/src/index.rs
+++ b/src/index.rs
@@ -1,5 +1,6 @@
-use std::collections::hash_map::HashMap;
+use std::collections::HashSet;
 use std::fs::{self, OpenOptions};
+use std::hash::{Hash, Hasher};
 use std::io::{ErrorKind, Write};
 use std::path::{Path, PathBuf};
 use std::time::{SystemTime, UNIX_EPOCH};
@@ -36,7 +37,7 @@ pub struct Entry {
     pub metadata: Value,
 }
 
-#[derive(Deserialize, Serialize, PartialEq, Debug)]
+#[derive(Deserialize, Serialize, Debug)]
 struct SerializableEntry {
     key: String,
     integrity: Option<String>,
@@ -45,6 +46,20 @@ struct SerializableEntry {
     metadata: Value,
 }
 
+impl PartialEq for SerializableEntry {
+    fn eq(&self, other: &Self) -> bool {
+        self.key == other.key
+    }
+}
+
+impl Eq for SerializableEntry {}
+
+impl Hash for SerializableEntry {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.key.hash(state);
+    }
+}
+
 pub fn insert(cache: &Path, key: &str, opts: PutOpts) -> Result<Integrity, Error> {
     let bucket = bucket_path(&cache, &key);
     if let Some(path) = mkdirp::mkdirp(bucket.parent().unwrap())? {
@@ -57,16 +72,15 @@ pub fn insert(cache: &Path, key: &str, opts: PutOpts) -> Result<Integrity, Error
         size: opts.size.unwrap_or(0),
         metadata: opts.metadata.unwrap_or_else(|| json!(null)),
     })?;
-    let str = format!("\n{}\t{}", hash_entry(&stringified), stringified);
-    OpenOptions::new()
-        .create(true)
-        .append(true)
-        .open(&bucket)?
-        .write_all(&str.into_bytes())?;
+
+    let mut buck = OpenOptions::new().create(true).append(true).open(&bucket)?;
+
+    write!(buck, "\n{}\t{}", hash_entry(&stringified), stringified)?;
     chownr::chownr(&bucket, opts.uid, opts.gid)?;
     Ok(opts
         .sri
-        .unwrap_or_else(|| "sha1-deadbeef".parse::<Integrity>().unwrap()))
+        .or_else(|| "sha1-deadbeef".parse::<Integrity>().ok())
+        .unwrap())
 }
 
 pub fn find(cache: &Path, key: &str) -> Result<Option<Entry>, Error> {
@@ -109,40 +123,37 @@ pub fn delete(cache: &Path, key: &str) -> Result<(), Error> {
             uid: None,
             gid: None,
         },
-    )?;
-    Ok(())
+    )
+    .map(|_| ())
 }
 
 pub fn ls(cache: &Path) -> impl Iterator<Item = Result<Entry, Error>> {
-    let mut path = PathBuf::new();
-    path.push(cache);
-    path.push(format!("index-v{}", INDEX_VERSION));
-    WalkDir::new(path)
+    WalkDir::new(cache.join(format!("index-v{}", INDEX_VERSION)))
         .into_iter()
         .map(|bucket| {
             let bucket = bucket?;
             if bucket.file_type().is_dir() {
-                return Ok(core::iter::empty().collect::<Vec<Entry>>());
+                return Ok(Vec::new());
             }
-            let entries = bucket_entries(bucket.path())?;
-            let mut dedupe: HashMap<String, SerializableEntry> = HashMap::new();
-            for entry in entries {
-                dedupe.insert(entry.key.clone(), entry);
-            }
-            let iter = dedupe
+
+            Ok(bucket_entries(bucket.path())?
                 .into_iter()
-                .filter(|se| se.1.integrity.is_some())
-                .map(|se| {
-                    let se = se.1;
-                    Entry {
-                        key: se.key,
-                        integrity: se.integrity.unwrap().parse().unwrap(),
-                        time: se.time,
-                        size: se.size,
-                        metadata: se.metadata,
+                .collect::<HashSet<SerializableEntry>>()
+                .into_iter()
+                .filter_map(|se| {
+                    if let Some(i) = se.integrity {
+                        Some(Entry {
+                            key: se.key,
+                            integrity: i.parse().unwrap(),
+                            time: se.time,
+                            size: se.size,
+                            metadata: se.metadata,
+                        })
+                    } else {
+                        None
                     }
-                });
-            Ok(iter.collect::<Vec<Entry>>())
+                })
+                .collect())
         })
         .flat_map(|res| match res {
             Ok(it) => Left(it.into_iter().map(Ok)),
@@ -152,13 +163,11 @@ pub fn ls(cache: &Path) -> impl Iterator<Item = Result<Entry, Error>> {
 
 fn bucket_path(cache: &Path, key: &str) -> PathBuf {
     let hashed = hash_key(&key);
-    let mut path = PathBuf::new();
-    path.push(cache);
-    path.push(format!("index-v{}", INDEX_VERSION));
-    path.push(&hashed[0..2]);
-    path.push(&hashed[2..4]);
-    path.push(&hashed[4..]);
-    path
+    cache
+        .join(format!("index-v{}", INDEX_VERSION))
+        .join(&hashed[0..2])
+        .join(&hashed[2..4])
+        .join(&hashed[4..])
 }
 
 fn hash_key(key: &str) -> String {
@@ -181,33 +190,29 @@ fn now() -> u128 {
 }
 
 fn bucket_entries(bucket: &Path) -> Result<Vec<SerializableEntry>, Error> {
-    let lines = match fs::read_to_string(bucket) {
-        Ok(data) => Ok(data),
-        Err(ref e) if e.kind() == ErrorKind::NotFound => Ok(String::from("")),
-        err => err,
-    }?;
-    Ok(lines.split('\n').fold(vec![], |mut acc, entry: &str| {
-        if entry.is_empty() {
-            return acc;
-        }
-        let entry_str = match entry.split('\t').collect::<Vec<&str>>()[..] {
-            [hash, entry_str] => {
-                if hash_entry(entry_str) != hash {
-                    // Hash is no good! Corruption or malice? Doesn't matter!
-                    // EJECT EJECT
-                    return acc;
-                } else {
-                    entry_str
-                }
+    use std::io::{BufRead, BufReader};
+    fs::File::open(bucket)
+        .map(|file| {
+            BufReader::new(file)
+                .lines()
+                .filter_map(Result::ok)
+                .filter_map(|entry| {
+                    let entry_str = match entry.split('\t').collect::<Vec<&str>>()[..] {
+                        [hash, entry_str] if hash_entry(entry_str) == hash => entry_str,
+                        // Something's wrong with the entry. Abort.
+                        _ => return None,
+                    };
+                    serde_json::from_str::<SerializableEntry>(entry_str).ok()
+                })
+                .collect()
+        })
+        .or_else(|err| {
+            if err.kind() == ErrorKind::NotFound {
+                Ok(Vec::new())
+            } else {
+                Err(err.into())
             }
-            // Something's wrong with the entry. Abort.
-            _ => return acc,
-        };
-        if let Ok(entry) = serde_json::from_str::<SerializableEntry>(entry_str) {
-            acc.push(entry)
-        }
-        acc
-    }))
+        })
 }
 
 #[cfg(test)]
diff --git a/src/lib.rs b/src/lib.rs
index a7f6b37..eb21178 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,8 +4,8 @@
 
 #![warn(missing_docs, missing_doc_code_examples)]
 
-pub use ssri::Algorithm;
 pub use serde_json::Value;
+pub use ssri::Algorithm;
 
 mod content;
 mod errors;