diff --git a/Cargo.lock b/Cargo.lock
index 6d5dd22..9ac93cc 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -18,9 +18,9 @@ dependencies = [
 
 [[package]]
 name = "actix-http"
-version = "3.0.0-beta.4"
+version = "3.0.0-beta.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8a01f9e0681608afa887d4269a0857ac4226f09ba5ceda25939e8391c9da610a"
+checksum = "fb9c5d7ceb490d6565156ae1d4d467db17da1759425c65a2e36ac5e182e014e2"
 dependencies = [
  "actix-codec",
  "actix-rt",
@@ -33,7 +33,6 @@ dependencies = [
  "brotli2",
  "bytes",
  "bytestring",
- "cfg-if",
  "cookie",
  "derive_more",
  "encoding_rs",
@@ -45,11 +44,13 @@ dependencies = [
  "httparse",
  "itoa",
  "language-tags",
+ "local-channel",
  "log",
  "mime",
  "once_cell",
  "percent-encoding",
  "pin-project",
+ "pin-project-lite",
  "rand",
  "regex",
  "serde",
@@ -86,9 +87,9 @@ dependencies = [
 
 [[package]]
 name = "actix-rt"
-version = "2.1.0"
+version = "2.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0b4e57bc1a3915e71526d128baf4323700bd1580bc676239e2298a4c5b001f18"
+checksum = "bc7d7cd957c9ed92288a7c3c96af81fa5291f65247a76a34dac7b6af74e52ba0"
 dependencies = [
  "actix-macros",
  "futures-core",
@@ -97,11 +98,10 @@ dependencies = [
 
 [[package]]
 name = "actix-server"
-version = "2.0.0-beta.3"
+version = "2.0.0-beta.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a99198727204a48f82559c18e4b0ba3197b97d5f4576a32bdbef371f3b4599c1"
+checksum = "0872f02a1871257ef09c5a269dce5dc5fea5ccf502adbf5d39f118913b61411c"
 dependencies = [
- "actix-codec",
  "actix-rt",
  "actix-service",
  "actix-utils",
@@ -125,9 +125,9 @@ dependencies = [
 
 [[package]]
 name = "actix-tls"
-version = "3.0.0-beta.4"
+version = "3.0.0-beta.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d2b1455e3f7a26d40cfc1080b571f41e8165e5a88e937ed579f7a4b3d55b0370"
+checksum = "65b7bb60840962ef0332f7ea01a57d73a24d2cb663708511ff800250bbfef569"
 dependencies = [
  "actix-codec",
  "actix-rt",
@@ -144,24 +144,19 @@ dependencies = [
 
 [[package]]
 name = "actix-utils"
-version = "3.0.0-beta.2"
+version = "3.0.0-beta.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "458795e09a29bc5557604f9ff6f32236fd0ee457d631672e4ec8f6a0103bb292"
+checksum = "c7e96334417549752384b169ca5d52bcea9e5081dbb2d3933599ac8b770f642a"
 dependencies = [
- "actix-codec",
- "actix-rt",
- "actix-service",
- "futures-core",
- "futures-sink",
- "log",
+ "local-waker",
  "pin-project-lite",
 ]
 
 [[package]]
 name = "actix-web"
-version = "4.0.0-beta.4"
+version = "4.0.0-beta.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1d95e50c9e32e8456220b5804867de76e97a86ab8c38b51c9edcccc0f0fddca7"
+checksum = "6de19cc341c2e68b1ee126de171e86b610b5bbcecc660d1250ebed73e0257bd6"
 dependencies = [
  "actix-codec",
  "actix-http",
@@ -174,23 +169,23 @@ dependencies = [
  "actix-utils",
  "actix-web-codegen",
  "ahash 0.7.2",
- "awc",
  "bytes",
  "derive_more",
  "either",
  "encoding_rs",
  "futures-core",
  "futures-util",
+ "language-tags",
  "log",
  "mime",
+ "once_cell",
  "pin-project",
  "regex",
- "rustls",
  "serde",
  "serde_json",
  "serde_urlencoded",
  "smallvec",
- "socket2 0.3.19",
+ "socket2",
  "time 0.2.26",
  "url",
 ]
@@ -390,33 +385,6 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cdb031dd78e28731d87d56cc8ffef4a8f36ca26c38fe2de700543e627f8a464a"
 
-[[package]]
-name = "awc"
-version = "3.0.0-beta.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "09aecd8728f6491a62b27454ea4b36fb7e50faf32928b0369b644e402c651f4e"
-dependencies = [
- "actix-codec",
- "actix-http",
- "actix-rt",
- "actix-service",
- "base64 0.13.0",
- "bytes",
- "cfg-if",
- "derive_more",
- "futures-core",
- "itoa",
- "log",
- "mime",
- "percent-encoding",
- "pin-project-lite",
- "rand",
- "rustls",
- "serde",
- "serde_json",
- "serde_urlencoded",
-]
-
 [[package]]
 name = "base-x"
 version = "0.2.8"
@@ -661,9 +629,9 @@ dependencies = [
 
 [[package]]
 name = "const_fn"
-version = "0.4.5"
+version = "0.4.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "28b9d6de7f49e22cf97ad17fc4036ece69300032f45f78f30b4a4482cdc3f4a6"
+checksum = "076a6803b0dacd6a88cfe64deba628b01533ff5ef265687e6938280c1afd0a28"
 
 [[package]]
 name = "convert_case"
@@ -1075,9 +1043,9 @@ checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
 
 [[package]]
 name = "http"
-version = "0.2.3"
+version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7245cd7449cc792608c3c8a9eaf69bd4eabbabf802713748fd739c98b82f0747"
+checksum = "527e8c9ac747e28542699a951517aa9a6945af506cd1f2e1b53a576c17b6cc11"
 dependencies = [
  "bytes",
  "fnv",
@@ -1097,9 +1065,9 @@ dependencies = [
 
 [[package]]
 name = "httparse"
-version = "1.3.5"
+version = "1.3.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "615caabe2c3160b313d52ccc905335f4ed5f10881dd63dc5699d47e90be85691"
+checksum = "bc35c995b9d93ec174cf9a27d425c7892722101e14993cd227fdb51d70cf9589"
 
 [[package]]
 name = "httpdate"
@@ -1109,9 +1077,9 @@ checksum = "494b4d60369511e7dea41cf646832512a94e542f68bb9c49e54518e0f468eb47"
 
 [[package]]
 name = "hyper"
-version = "0.14.4"
+version = "0.14.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e8e946c2b1349055e0b72ae281b238baf1a3ea7307c7e9f9d64673bdd9c26ac7"
+checksum = "8bf09f61b52cfcf4c00de50df88ae423d6c02354e385a86341133b5338630ad1"
 dependencies = [
  "bytes",
  "futures-channel",
@@ -1124,7 +1092,7 @@ dependencies = [
  "httpdate",
  "itoa",
  "pin-project",
- "socket2 0.3.19",
+ "socket2",
  "tokio",
  "tower-service",
  "tracing",
@@ -1188,9 +1156,9 @@ checksum = "dd25036021b0de88a0aff6b850051563c6516d0bf53f8638938edbb9de732736"
 
 [[package]]
 name = "js-sys"
-version = "0.3.49"
+version = "0.3.50"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dc15e39392125075f60c95ba416f5381ff6c3a948ff02ab12464715adf56c821"
+checksum = "2d99f9e3e84b8f67f846ef5b4cbbc3b1c29f6c759fcbce6f01aa0e73d932a24c"
 dependencies = [
  "wasm-bindgen",
 ]
@@ -1218,9 +1186,9 @@ checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
 [[package]]
 name = "libc"
-version = "0.2.91"
+version = "0.2.93"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8916b1f6ca17130ec6568feccee27c156ad12037880833a3b842a823236502e7"
+checksum = "9385f66bf6105b241aa65a61cb923ef20efc665cb9f9bb50ac2f0c4b7f378d41"
 
 [[package]]
 name = "libsodium-sys"
@@ -1234,10 +1202,28 @@ dependencies = [
 ]
 
 [[package]]
-name = "lock_api"
-version = "0.4.2"
+name = "local-channel"
+version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dd96ffd135b2fd7b973ac026d28085defbe8983df057ced3eb4f2130b0831312"
+checksum = "6246c68cf195087205a0512559c97e15eaf95198bf0e206d662092cdcb03fe9f"
+dependencies = [
+ "futures-core",
+ "futures-sink",
+ "futures-util",
+ "local-waker",
+]
+
+[[package]]
+name = "local-waker"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "84f9a2d3e27ce99ce2c3aad0b09b1a7b916293ea9b2bf624c13fe646fadd8da4"
+
+[[package]]
+name = "lock_api"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a3c91c24eae6777794bb1997ad98bbb87daf92890acab859f7eaa4320333176"
 dependencies = [
  "scopeguard",
 ]
@@ -1277,6 +1263,7 @@ dependencies = [
  "futures",
  "log",
  "lru",
+ "once_cell",
  "parking_lot",
  "reqwest",
  "rustls",
@@ -1286,6 +1273,7 @@ dependencies = [
  "sodiumoxide",
  "ssri",
  "thiserror",
+ "tokio",
  "url",
 ]
 
@@ -1374,7 +1362,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a19900e7eee95eb2b3c2e26d12a874cc80aaf750e31be6fcbe743ead369fa45d"
 dependencies = [
  "libc",
- "socket2 0.4.0",
+ "socket2",
 ]
 
 [[package]]
@@ -1616,9 +1604,9 @@ checksum = "bc881b2c22681370c6a780e47af9840ef841837bc98118431d4e1868bd0c1086"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.24"
+version = "1.0.26"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e0704ee1a7e00d7bb417d0770ea303c1bccbabf0ef1667dae92b5967f5f8a71"
+checksum = "a152013215dca273577e18d2bf00fa862b89b24169fb78c4c95aeb07992c9cec"
 dependencies = [
  "unicode-xid",
 ]
@@ -1822,9 +1810,9 @@ dependencies = [
 
 [[package]]
 name = "security-framework"
-version = "2.1.2"
+version = "2.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d493c5f39e02dfb062cd8f33301f90f9b13b650e8c1b1d0fd75c19dd64bff69d"
+checksum = "3670b1d2fdf6084d192bc71ead7aabe6c06aa2ea3fbd9cc3ac111fa5c2b1bd84"
 dependencies = [
  "bitflags",
  "core-foundation",
@@ -1835,9 +1823,9 @@ dependencies = [
 
 [[package]]
 name = "security-framework-sys"
-version = "2.1.1"
+version = "2.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dee48cdde5ed250b0d3252818f646e174ab414036edb884dde62d80a3ac6082d"
+checksum = "3676258fd3cfe2c9a0ec99ce3038798d847ce3e4bb17746373eb9f0f1ac16339"
 dependencies = [
  "core-foundation-sys",
  "libc",
@@ -1946,9 +1934,9 @@ dependencies = [
 
 [[package]]
 name = "signal-hook"
-version = "0.3.7"
+version = "0.3.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6aa894ef3fade0ee7243422f4fbbd6c2b48e6de767e621d37ef65f2310f53cea"
+checksum = "ef33d6d0cd06e0840fba9985aab098c147e67e05cee14d412d3345ed14ff30ac"
 dependencies = [
  "libc",
  "signal-hook-registry",
@@ -1988,17 +1976,6 @@ version = "1.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fe0f37c9e8f3c5a4a66ad655a93c74daac4ad00c441533bf5c6e7990bb42604e"
 
-[[package]]
-name = "socket2"
-version = "0.3.19"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "122e570113d28d773067fab24266b66753f6ea915758651696b6e35e49f88d6e"
-dependencies = [
- "cfg-if",
- "libc",
- "winapi",
-]
-
 [[package]]
 name = "socket2"
 version = "0.4.0"
@@ -2108,9 +2085,9 @@ checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
 
 [[package]]
 name = "syn"
-version = "1.0.64"
+version = "1.0.69"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3fd9d1e9976102a03c542daa2eff1b43f9d72306342f3f8b3ed5fb8908195d6f"
+checksum = "48fe99c6bd8b1cc636890bcc071842de909d902c81ac7dab53ba33c421ab8ffb"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -2230,9 +2207,9 @@ dependencies = [
 
 [[package]]
 name = "tinyvec"
-version = "1.1.1"
+version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "317cca572a0e89c3ce0ca1f1bdc9369547fe318a683418e42ac8f59d14701023"
+checksum = "5b5220f05bb7de7f3f53c7c065e1199b3172696fe2db9f9c4d8ad9b4ee74c342"
 dependencies = [
  "tinyvec_macros",
 ]
@@ -2254,13 +2231,26 @@ dependencies = [
  "libc",
  "memchr",
  "mio",
+ "num_cpus",
  "once_cell",
  "parking_lot",
  "pin-project-lite",
  "signal-hook-registry",
+ "tokio-macros",
  "winapi",
 ]
 
+[[package]]
+name = "tokio-macros"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "caf7b11a536f46a809a8a9f0bb4237020f70ecbf115b842360afb127ea2fda57"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "tokio-native-tls"
 version = "0.3.0"
@@ -2336,9 +2326,9 @@ checksum = "879f6906492a7cd215bfa4cf595b600146ccfac0c79bcbd1f3000162af5e8b06"
 
 [[package]]
 name = "unicode-bidi"
-version = "0.3.4"
+version = "0.3.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "49f2bd0c6468a8230e1db229cff8029217cf623c767ea5d60bfbd42729ea54d5"
+checksum = "eeb8be209bb1c96b7c177c7420d26e04eccacb0eeae6b980e35fcb74678107e0"
 dependencies = [
  "matches",
 ]
@@ -2457,9 +2447,9 @@ checksum = "fd6fbd9a79829dd1ad0cc20627bf1ed606756a7f77edff7b66b7064f9cb327c6"
 
 [[package]]
 name = "wasm-bindgen"
-version = "0.2.72"
+version = "0.2.73"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8fe8f61dba8e5d645a4d8132dc7a0a66861ed5e1045d2c0ed940fab33bac0fbe"
+checksum = "83240549659d187488f91f33c0f8547cbfef0b2088bc470c116d1d260ef623d9"
 dependencies = [
  "cfg-if",
  "serde",
@@ -2469,9 +2459,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-backend"
-version = "0.2.72"
+version = "0.2.73"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "046ceba58ff062da072c7cb4ba5b22a37f00a302483f7e2a6cdc18fedbdc1fd3"
+checksum = "ae70622411ca953215ca6d06d3ebeb1e915f0f6613e3b495122878d7ebec7dae"
 dependencies = [
  "bumpalo",
  "lazy_static",
@@ -2484,9 +2474,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-futures"
-version = "0.4.22"
+version = "0.4.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "73157efb9af26fb564bb59a009afd1c7c334a44db171d280690d0c3faaec3468"
+checksum = "81b8b767af23de6ac18bf2168b690bed2902743ddf0fb39252e36f9e2bfc63ea"
 dependencies = [
  "cfg-if",
  "js-sys",
@@ -2496,9 +2486,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-macro"
-version = "0.2.72"
+version = "0.2.73"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0ef9aa01d36cda046f797c57959ff5f3c615c9cc63997a8d545831ec7976819b"
+checksum = "3e734d91443f177bfdb41969de821e15c516931c3c3db3d318fa1b68975d0f6f"
 dependencies = [
  "quote",
  "wasm-bindgen-macro-support",
@@ -2506,9 +2496,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-macro-support"
-version = "0.2.72"
+version = "0.2.73"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "96eb45c1b2ee33545a813a92dbb53856418bf7eb54ab34f7f7ff1448a5b3735d"
+checksum = "d53739ff08c8a68b0fdbcd54c372b8ab800b1449ab3c9d706503bc7dd1621b2c"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -2519,15 +2509,15 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-shared"
-version = "0.2.72"
+version = "0.2.73"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b7148f4696fb4960a346eaa60bbfb42a1ac4ebba21f750f75fc1375b098d5ffa"
+checksum = "d9a543ae66aa233d14bb765ed9af4a33e81b8b58d1584cf1b47ff8cd0b9e4489"
 
 [[package]]
 name = "web-sys"
-version = "0.3.49"
+version = "0.3.50"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "59fe19d70f5dacc03f6e46777213facae5ac3801575d56ca6cbd4c93dcd12310"
+checksum = "a905d57e488fec8861446d3393670fb50d27a262344013181c2cdf9fff5481be"
 dependencies = [
  "js-sys",
  "wasm-bindgen",
@@ -2545,9 +2535,9 @@ dependencies = [
 
 [[package]]
 name = "webpki-roots"
-version = "0.21.0"
+version = "0.21.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "82015b7e0b8bad8185994674a13a93306bea76cf5a16c5a181382fd3a5ec2376"
+checksum = "aabe153544e473b775453675851ecc86863d2a81d786d741f6b76778f2a48940"
 dependencies = [
  "webpki",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 2fd1f40..e89fdc2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,8 +19,9 @@ clap = { version = "3.0.0-beta.2", features = [ "wrap_help" ] }
 ctrlc = "3"
 dotenv = "0.15"
 futures = "0.3"
+once_cell = "1"
 parking_lot = "0.11"
-reqwest = { version = "0.11", features = [ "json" ] }
+reqwest = { version = "0.11", features = [ "json", "stream" ] }
 log = "0.4"
 lru = "0.6"
 rustls = "0.19"
@@ -30,6 +31,7 @@ simple_logger = "1"
 sodiumoxide = "0.2"
 ssri = "5"
 thiserror = "1"
+tokio = { version = "1", features = [ "full" ] }
 url = { version = "2", features = [ "serde" ] }
 
 [profile.release]
diff --git a/src/fs.rs b/src/fs.rs
new file mode 100644
index 0000000..1fc6d81
--- /dev/null
+++ b/src/fs.rs
@@ -0,0 +1,153 @@
+use std::task::{Context, Poll};
+use std::{collections::HashMap, path::PathBuf};
+use std::{path::Path, sync::atomic::Ordering};
+use std::{pin::Pin, sync::atomic::AtomicU8};
+use std::{sync::Arc, time::Duration};
+
+use bytes::{Bytes, BytesMut};
+use futures::{Future, Stream, StreamExt};
+use once_cell::sync::Lazy;
+use parking_lot::RwLock;
+use reqwest::Error;
+use tokio::fs::{remove_file, File, OpenOptions};
+use tokio::io::{AsyncRead, AsyncWriteExt, ReadBuf};
+use tokio::time::Sleep;
+
+static WRITING_STATUS: Lazy<RwLock<HashMap<PathBuf, Arc<CacheStatus>>>> =
+    Lazy::new(|| RwLock::new(HashMap::new()));
+
+pub async fn transparent_file_stream(
+    path: &Path,
+    mut byte_stream: impl Stream<Item = Result<Bytes, Error>> + Unpin + Send + 'static,
+) -> Result<impl Stream<Item = Result<Bytes, UpstreamError>>, std::io::Error> {
+    if let Some(arc) = WRITING_STATUS.read().get(path) {
+        FromFsStream::new(path, Arc::clone(&arc)).await
+    } else {
+        let done_writing_flag = Arc::new(CacheStatus::new());
+
+        {
+            let mut write_lock = WRITING_STATUS.write();
+            File::create(path).await?; // we need to make sure the file exists and is truncated.
+            write_lock.insert(path.to_path_buf(), Arc::clone(&done_writing_flag));
+        }
+
+        let write_flag = Arc::clone(&done_writing_flag);
+        // need owned variant because async lifetime
+        let mut file = OpenOptions::new().write(true).open(path).await?;
+        let path_buf = path.to_path_buf();
+        tokio::spawn(async move {
+            let path_buf = path_buf; // moves path buf into async
+            let mut was_errored = false;
+            while let Some(bytes) = byte_stream.next().await {
+                match bytes {
+                    Ok(bytes) => file.write_all(&bytes).await?,
+                    Err(_) => was_errored = true,
+                }
+            }
+
+            if was_errored {
+                // It's ok if the deleting the file fails, since we truncate on
+                // create anyways
+                let _ = remove_file(&path_buf).await;
+            } else {
+                file.flush().await?;
+                file.sync_all().await?;
+            }
+
+            let mut write_lock = WRITING_STATUS.write();
+            // This needs to be written atomically with the write lock, else
+            // it's possible we have an inconsistent state
+            if was_errored {
+                write_flag.store(WritingStatus::Error);
+            } else {
+                write_flag.store(WritingStatus::Done);
+            }
+            write_lock.remove(&path_buf);
+
+            // We don't ever check this, so the return value doesn't matter
+            Ok::<_, std::io::Error>(())
+        });
+
+        FromFsStream::new(path, Arc::clone(&done_writing_flag)).await
+    }
+}
+
+struct FromFsStream {
+    file: Pin<Box<File>>,
+    sleep: Pin<Box<Sleep>>,
+    is_file_done_writing: Arc<CacheStatus>,
+}
+
+impl FromFsStream {
+    async fn new(path: &Path, is_done: Arc<CacheStatus>) -> Result<Self, std::io::Error> {
+        Ok(Self {
+            file: Box::pin(File::open(path).await?),
+            // 0.5ms
+            sleep: Box::pin(tokio::time::sleep(Duration::from_micros(500))),
+            is_file_done_writing: is_done,
+        })
+    }
+}
+
+/// Represents some upstream error.
+struct UpstreamError;
+
+impl Stream for FromFsStream {
+    type Item = Result<Bytes, UpstreamError>;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        let status = self.is_file_done_writing.load();
+
+        let mut bytes = BytesMut::with_capacity(1460);
+        let mut buffer = ReadBuf::new(&mut bytes);
+        let polled_result = self.file.as_mut().poll_read(cx, &mut buffer);
+
+        match (status, buffer.filled().len()) {
+            // Prematurely reached EOF, schedule a poll in the future
+            (WritingStatus::NotDone, 0) => {
+                let _ = self.sleep.as_mut().poll(cx);
+                Poll::Pending
+            }
+            // We got an error, abort the read.
+            (WritingStatus::Error, _) => Poll::Ready(Some(Err(UpstreamError))),
+            _ => polled_result.map(|_| Some(Ok(bytes.split().into()))),
+        }
+    }
+}
+
+struct CacheStatus(AtomicU8);
+
+impl CacheStatus {
+    #[inline]
+    fn new() -> Self {
+        Self(AtomicU8::new(WritingStatus::NotDone as u8))
+    }
+
+    #[inline]
+    fn store(&self, status: WritingStatus) {
+        self.0.store(status as u8, Ordering::Release);
+    }
+
+    #[inline]
+    fn load(&self) -> WritingStatus {
+        self.0.load(Ordering::Acquire).into()
+    }
+}
+
+enum WritingStatus {
+    NotDone = 0,
+    Done,
+    Error,
+}
+
+impl From<u8> for WritingStatus {
+    #[inline]
+    fn from(v: u8) -> Self {
+        match v {
+            0 => Self::NotDone,
+            1 => Self::Done,
+            2 => Self::Error,
+            _ => unreachable!(),
+        }
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index ad901a9..279282d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -25,6 +25,7 @@ use thiserror::Error;
 
 mod cache;
 mod config;
+mod fs;
 mod ping;
 mod routes;
 mod state;
diff --git a/src/routes.rs b/src/routes.rs
index 4f7dc71..7382431 100644
--- a/src/routes.rs
+++ b/src/routes.rs
@@ -285,5 +285,5 @@ fn construct_response(cached: &CachedImage) -> ServerResponse {
         resp.append_header((LAST_MODIFIED, &**last_modified));
     }
 
-    return ServerResponse::HttpResponse(push_headers(&mut resp).streaming(stream::iter(data)));
+    ServerResponse::HttpResponse(push_headers(&mut resp).streaming(stream::iter(data)))
 }