refactor: rewrite HTTP cache for file fetcher (#4030)

1 files changed, 195 insertions, 0 deletions

diff --git a/cli/http_cache.rs b/cli/http_cache.rs
new file mode 100644
index 000000000..4a604efd2
--- /dev/null
+++ b/cli/http_cache.rs
@@ -0,0 +1,195 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+/// This module is meant to eventually implement HTTP cache
+/// as defined in RFC 7234 (https://tools.ietf.org/html/rfc7234).
+/// Currently it's a very simplified version to fulfill Deno needs
+/// at hand.
+use crate::fs as deno_fs;
+use crate::http_util::HeadersMap;
+use deno_core::ErrBox;
+use std::fs;
+use std::fs::File;
+use std::path::Path;
+use std::path::PathBuf;
+use url::Url;
+
+/// Turn base of url (scheme, hostname, port) into a valid filename.
+/// This method replaces port part with a special string token (because
+/// ":" cannot be used in filename on some platforms).
+pub fn base_url_to_filename(url: &Url) -> PathBuf {
+  let mut out = PathBuf::new();
+
+  let scheme = url.scheme();
+  out.push(scheme);
+
+  match scheme {
+    "http" | "https" => {
+      let host = url.host_str().unwrap();
+      let host_port = match url.port() {
+        Some(port) => format!("{}_PORT{}", host, port),
+        None => host.to_string(),
+      };
+      out.push(host_port);
+    }
+    scheme => {
+      unimplemented!(
+        "Don't know how to create cache name for scheme: {}",
+        scheme
+      );
+    }
+  };
+
+  out
+}
+
+/// Turn provided `url` into a hashed filename.
+/// URLs can contain a lot of characters that cannot be used
+/// in filenames (like "?", "#", ":"), so in order to cache
+/// them properly they are deterministically hashed into ASCII
+/// strings.
+///
+/// NOTE: this method is `pub` because it's used in integration_tests
+pub fn url_to_filename(url: &Url) -> PathBuf {
+  let mut cache_filename = base_url_to_filename(url);
+
+  let mut rest_str = url.path().to_string();
+  if let Some(query) = url.query() {
+    rest_str.push_str("?");
+    rest_str.push_str(query);
+  }
+  // NOTE: fragment is omitted on purpose - it's not taken into
+  // account when caching - it denotes parts of webpage, which
+  // in case of static resources doesn't make much sense
+  let hashed_filename = crate::checksum::gen(vec![rest_str.as_bytes()]);
+  cache_filename.push(hashed_filename);
+  cache_filename
+}
+
+#[derive(Clone)]
+pub struct HttpCache {
+  pub location: PathBuf,
+}
+
+impl HttpCache {
+  /// Returns error if unable to create directory
+  /// at specified location.
+  pub fn new(location: &Path) -> Result<Self, ErrBox> {
+    fs::create_dir_all(&location)?;
+    Ok(Self {
+      location: location.to_owned(),
+    })
+  }
+
+  pub(crate) fn get_cache_filename(&self, url: &Url) -> PathBuf {
+    self.location.join(url_to_filename(url))
+  }
+
+  // TODO(bartlomieju): this method should check headers file
+  // and validate against ETAG/Last-modified-as headers.
+  // ETAG check is currently done in `cli/file_fetcher.rs`.
+  pub fn get(&self, url: &Url) -> Result<(File, HeadersMap), ErrBox> {
+    let cache_filename = self.location.join(url_to_filename(url));
+    let headers_filename = cache_filename.with_extension("headers.json");
+    let file = File::open(cache_filename)?;
+    let headers_json = fs::read_to_string(headers_filename)?;
+    let headers_map: HeadersMap = serde_json::from_str(&headers_json)?;
+    Ok((file, headers_map))
+  }
+
+  pub fn set(
+    &self,
+    url: &Url,
+    headers_map: HeadersMap,
+    content: &[u8],
+  ) -> Result<(), ErrBox> {
+    let cache_filename = self.location.join(url_to_filename(url));
+    let headers_filename = cache_filename.with_extension("headers.json");
+    // Create parent directory
+    let parent_filename = cache_filename
+      .parent()
+      .expect("Cache filename should have a parent dir");
+    fs::create_dir_all(parent_filename)?;
+    // Cache content
+    deno_fs::write_file(&cache_filename, content, 0o666)?;
+    let serialized_headers = serde_json::to_string(&headers_map)?;
+    // Cache headers
+    deno_fs::write_file(&headers_filename, serialized_headers, 0o666)?;
+    Ok(())
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+  use std::collections::HashMap;
+  use std::io::Read;
+  use tempfile::TempDir;
+
+  #[test]
+  fn test_create_cache() {
+    let dir = TempDir::new().unwrap();
+    let mut cache_path = dir.path().to_owned();
+    cache_path.push("foobar");
+    let r = HttpCache::new(&cache_path);
+    assert!(r.is_ok());
+    assert!(cache_path.is_dir());
+  }
+
+  #[test]
+  fn test_get_set() {
+    let dir = TempDir::new().unwrap();
+    let cache = HttpCache::new(dir.path()).unwrap();
+    let url = Url::parse("https://deno.land/x/welcome.ts").unwrap();
+    let mut headers = HashMap::new();
+    headers.insert(
+      "content-type".to_string(),
+      "application/javascript".to_string(),
+    );
+    headers.insert("etag".to_string(), "as5625rqdsfb".to_string());
+    let content = b"Hello world";
+    let r = cache.set(&url, headers, content);
+    eprintln!("result {:?}", r);
+    assert!(r.is_ok());
+    let r = cache.get(&url);
+    assert!(r.is_ok());
+    let (mut file, headers) = r.unwrap();
+    let mut content = String::new();
+    file.read_to_string(&mut content).unwrap();
+    assert_eq!(content, "Hello world");
+    assert_eq!(
+      headers.get("content-type").unwrap(),
+      "application/javascript"
+    );
+    assert_eq!(headers.get("etag").unwrap(), "as5625rqdsfb");
+    assert_eq!(headers.get("foobar"), None);
+    drop(dir);
+  }
+
+  #[test]
+  fn test_url_to_filename() {
+    let test_cases = [
+      ("https://deno.land/x/foo.ts", "https/deno.land/2c0a064891b9e3fbe386f5d4a833bce5076543f5404613656042107213a7bbc8"),
+      (
+        "https://deno.land:8080/x/foo.ts",
+        "https/deno.land_PORT8080/2c0a064891b9e3fbe386f5d4a833bce5076543f5404613656042107213a7bbc8",
+      ),
+      ("https://deno.land/", "https/deno.land/8a5edab282632443219e051e4ade2d1d5bbc671c781051bf1437897cbdfea0f1"),
+      (
+        "https://deno.land/?asdf=qwer",
+        "https/deno.land/e4edd1f433165141015db6a823094e6bd8f24dd16fe33f2abd99d34a0a21a3c0",
+      ),
+      // should be the same as case above, fragment (#qwer) is ignored
+      // when hashing
+      (
+        "https://deno.land/?asdf=qwer#qwer",
+        "https/deno.land/e4edd1f433165141015db6a823094e6bd8f24dd16fe33f2abd99d34a0a21a3c0",
+      ),
+    ];
+
+    for (url, expected) in test_cases.iter() {
+      let u = Url::parse(url).unwrap();
+      let p = url_to_filename(&u);
+      assert_eq!(p, PathBuf::from(expected));
+    }
+  }
+}