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Impl graceful shutdown of backend on failure

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This commit is contained in:
Stephen Seo 2022-03-18 23:43:15 +09:00
parent 13f500b4f5
commit 6c47ce948b
5 changed files with 142 additions and 49 deletions
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48
back_end/Cargo.lock generated
View file

@ -157,6 +157,7 @@ name = "four_line_dropper_backend"
version = "0.1.0"
dependencies = [
"bytes",
"futures",
"rand",
"rusqlite",
"serde_json",
@ -164,6 +165,21 @@ dependencies = [
"warp",
]
[[package]]
name = "futures"
version = "0.3.21"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "f73fe65f54d1e12b726f517d3e2135ca3125a437b6d998caf1962961f7172d9e"
dependencies = [
"futures-channel",
"futures-core",
"futures-executor",
"futures-io",
"futures-sink",
"futures-task",
"futures-util",
]
[[package]]
name = "futures-channel"
version = "0.3.21"
@ -180,6 +196,34 @@ version = "0.3.21"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "0c09fd04b7e4073ac7156a9539b57a484a8ea920f79c7c675d05d289ab6110d3"
[[package]]
name = "futures-executor"
version = "0.3.21"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "9420b90cfa29e327d0429f19be13e7ddb68fa1cccb09d65e5706b8c7a749b8a6"
dependencies = [
"futures-core",
"futures-task",
"futures-util",
]
[[package]]
name = "futures-io"
version = "0.3.21"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "fc4045962a5a5e935ee2fdedaa4e08284547402885ab326734432bed5d12966b"
[[package]]
name = "futures-macro"
version = "0.3.21"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "33c1e13800337f4d4d7a316bf45a567dbcb6ffe087f16424852d97e97a91f512"
dependencies = [
"proc-macro2",
"quote",
"syn",
]
[[package]]
name = "futures-sink"
version = "0.3.21"
@ -198,9 +242,13 @@ version = "0.3.21"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "d8b7abd5d659d9b90c8cba917f6ec750a74e2dc23902ef9cd4cc8c8b22e6036a"
dependencies = [
"futures-channel",
"futures-core",
"futures-io",
"futures-macro",
"futures-sink",
"futures-task",
"memchr",
"pin-project-lite",
"pin-utils",
"slab",

1
back_end/Cargo.toml
View file

@ -12,3 +12,4 @@ serde_json = "1.0"
bytes = "1.1"
rusqlite = "0.27.0"
rand = "0.8.4"
futures = "0.3"

93
back_end/src/db_handler.rs
View file

@ -13,7 +13,7 @@ enum DBFirstRun {
fn init_conn(sqlite_path: &str, first_run: DBFirstRun) -> Result<Connection, String> {
if let Ok(conn) = Connection::open(sqlite_path) {
conn.execute("PRAGMA foreign_keys = ON;", [])
.expect("Should be able to enable \"foreign_keys\"");
.map_err(|e| format!("Should be able to handle \"foreign_keys\": {:?}", e))?;
let result = conn.execute(
"
CREATE TABLE players (id INTEGER PRIMARY KEY NOT NULL,
@ -53,53 +53,74 @@ fn init_conn(sqlite_path: &str, first_run: DBFirstRun) -> Result<Connection, Str
}
Ok(conn)
} else {
Err(String::from("Failed to get connection"))
Err(String::from("Failed to open connection"))
}
}
pub fn start_db_handler_thread(rx: Receiver<SyncSender<u32>>, sqlite_path: String) {
pub fn start_db_handler_thread(
rx: Receiver<SyncSender<u32>>,
sqlite_path: String,
shutdown_tx: SyncSender<()>,
) {
thread::spawn(move || {
// temporarily get conn which should initialize on first setup of db
if let Ok(_conn) = init_conn(&sqlite_path, DBFirstRun::FirstRun) {
} else {
println!("ERROR: Failed init sqlite db connection");
shutdown_tx.send(()).ok();
return;
}
loop {
let result = rx.recv();
//println!("db_handler: Got result from rx");
if let Ok(player_tx) = result {
//println!("db_handler: Got player_tx from rx");
// got request to create new player, create new player
let mut player_id: u32 = thread_rng().gen();
let conn = init_conn(&sqlite_path, DBFirstRun::NotFirstRun)
.expect("DB connection should be available");
loop {
let mut stmt = conn
.prepare("SELECT id FROM players WHERE id = ?;")
.expect("Should be able to prepare DB statement");
match stmt.query_row([player_id], |_row| Ok(())) {
Ok(_) => {
player_id = thread_rng().gen();
}
Err(_) => break,
}
}
conn.execute(
"INSERT INTO players (id, date_added) VALUES (?, datetime());",
[player_id],
)
.unwrap_or_else(|_| {
panic!("Should be able to insert new player with id {}", player_id)
});
player_tx
.send(player_id)
.expect("Should be able to send back valid player id");
} else {
println!("db_handler: Failed to get player_tx");
'outer: loop {
let rx_recv_result = rx.recv();
if let Err(e) = rx_recv_result {
println!("Failed to get player_tx: {:?}", e);
shutdown_tx.send(()).ok();
break;
}
let player_tx = rx_recv_result.unwrap();
// got request to create new player, create new player
let mut player_id: u32 = thread_rng().gen();
let conn_result = init_conn(&sqlite_path, DBFirstRun::NotFirstRun);
if let Err(e) = conn_result {
println!("Failed to get sqlite db connection: {:?}", e);
shutdown_tx.send(()).ok();
break;
}
let conn = conn_result.unwrap();
loop {
let stmt_result = conn.prepare("SELECT id FROM players WHERE id = ?;");
if let Err(e) = stmt_result {
println!("Failed to create sqlite statement: {:?}", e);
shutdown_tx.send(()).ok();
break 'outer;
}
let mut stmt = stmt_result.unwrap();
match stmt.query_row([player_id], |_row| Ok(())) {
Ok(_) => {
player_id = thread_rng().gen();
}
Err(_) => break,
}
}
let insert_result = conn.execute(
"INSERT INTO players (id, date_added) VALUES (?, datetime());",
[player_id],
);
if let Err(e) = insert_result {
println!("Failed to insert into sqlite db: {:?}", e);
shutdown_tx.send(()).ok();
break 'outer;
}
let send_result = player_tx.send(player_id);
if let Err(e) = send_result {
println!("Failed to send back player id: {:?}", e);
shutdown_tx.send(()).ok();
break 'outer;
}
send_result.unwrap();
// Pair up players
// TODO
} // loop end

18
back_end/src/json_handlers.rs
View file

@ -1,15 +1,18 @@
use std::{
sync::mpsc::{sync_channel, Receiver, SyncSender},
sync::mpsc::{sync_channel, SyncSender},
time::Duration,
};
use serde_json::Value;
pub fn handle_json(root: Value, tx: SyncSender<SyncSender<u32>>) -> Result<String, String> {
pub fn handle_json(
root: Value,
tx: SyncSender<SyncSender<u32>>,
_shutdown_tx: SyncSender<()>, // maybe used here, not sure if it will be
) -> Result<String, String> {
if let Some(Value::String(type_str)) = root.get("type") {
let (player_tx, player_rx) = sync_channel::<u32>(8);
match type_str.as_str() {
"pairing_request" => handle_pairing_request(tx, player_tx, player_rx),
"pairing_request" => handle_pairing_request(tx),
"check_pairing" => handle_check_pairing(root),
"place_token" => handle_place_token(root),
"disconnect" => handle_disconnect(root),
@ -21,11 +24,8 @@ pub fn handle_json(root: Value, tx: SyncSender<SyncSender<u32>>) -> Result<Strin
}
}
fn handle_pairing_request(
tx: SyncSender<SyncSender<u32>>,
player_tx: SyncSender<u32>,
player_rx: Receiver<u32>,
) -> Result<String, String> {
fn handle_pairing_request(tx: SyncSender<SyncSender<u32>>) -> Result<String, String> {
let (player_tx, player_rx) = sync_channel::<u32>(1);
if tx.send(player_tx).is_err() {
return Err("{\"type\":\"pairing_response\", \"status\":\"internal_error\"}".into());
}

31
back_end/src/main.rs
View file

@ -6,6 +6,7 @@ const SQLITE_DB_PATH: &str = "./fourLineDropper.db";
use std::sync::mpsc::{sync_channel, SyncSender};
use db_handler::start_db_handler_thread;
use tokio::sync::oneshot;
use warp::{Filter, Rejection};
#[tokio::main]
@ -13,19 +14,36 @@ async fn main() {
let (db_tx, db_rx) = sync_channel::<SyncSender<u32>>(32);
let db_tx_clone = db_tx.clone();
start_db_handler_thread(db_rx, SQLITE_DB_PATH.into());
let (shutdown_tx, shutdown_rx) = oneshot::channel::<()>();
// Required because shutdown_tx is not cloneable, and its "send" consumes
// itself.
let (s_helper_tx, s_helper_rx) = sync_channel::<()>(1);
std::thread::spawn(move || {
if let Ok(_unused_value) = s_helper_rx.recv() {
shutdown_tx
.send(())
.expect("Should be able to send shutdown signal");
}
});
start_db_handler_thread(db_rx, SQLITE_DB_PATH.into(), s_helper_tx.clone());
let route = warp::body::content_length_limit(1024 * 32)
.and(warp::body::bytes())
.and_then(move |bytes: bytes::Bytes| {
let db_tx_clone = db_tx_clone.clone();
let s_helper_tx_clone = s_helper_tx.clone();
async move {
let body_str_result = std::str::from_utf8(bytes.as_ref());
if let Ok(body_str) = body_str_result {
let json_result = serde_json::from_str(body_str);
if let Ok(json_value) = json_result {
Ok(json_handlers::handle_json(json_value, db_tx_clone)
.unwrap_or_else(|e| e))
Ok(
json_handlers::handle_json(json_value, db_tx_clone, s_helper_tx_clone)
.unwrap_or_else(|e| e),
)
} else {
Ok(String::from("{\"type\": \"invalid_syntax\"}"))
}
@ -35,5 +53,10 @@ async fn main() {
}
});
warp::serve(route).run(([0, 0, 0, 0], 1237)).await;
let (_addr, server) =
warp::serve(route).bind_with_graceful_shutdown(([0, 0, 0, 0], 1237), async move {
shutdown_rx.await.ok();
});
tokio::task::spawn(server).await.unwrap();
}