Implement Block GET/PUT with new schema

- `Arc`+`Mutex` is replaced by `parking_lot::RwLock,` decoupled
  Read+Write and ability to upgrade read locks into write locks if
  needed
- Schema has changed, `Db` is now a struct that implements `new()` to
  return a new instance of itself, pros/cons listed in code but tl;dr
  blockchain and pending transactions are separate now
- `custom_filters` now supports extracting Block json and Transaction
  json in separate functions too
- /block GET and PUT implemented, `Blocks` currently have one check
  (transactions appear in pending transaction)
- debug is working after something, dunno how I fixed it

8 files changed, 220 insertions, 56 deletions

diff --git a/Cargo.lock b/Cargo.lock
index c531d87..45ae0a0 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -108,6 +108,15 @@ dependencies = [
 ]
 
 [[package]]
+name = "cloudabi"
+version = "0.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ddfc5b9aa5d4507acaf872de71051dfd0e309860e88966e1051e462a077aac4f"
+dependencies = [
+ "bitflags",
+]
+
+[[package]]
 name = "cpuid-bool"
 version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -273,6 +282,7 @@ version = "0.1.0"
 dependencies = [
  "chrono",
  "log",
+ "parking_lot",
  "pretty_env_logger",
  "serde",
  "serde_json",
@@ -475,6 +485,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9385f66bf6105b241aa65a61cb923ef20efc665cb9f9bb50ac2f0c4b7f378d41"
 
 [[package]]
+name = "lock_api"
+version = "0.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4da24a77a3d8a6d4862d95f72e6fdb9c09a643ecdb402d754004a557f2bec75"
+dependencies = [
+ "scopeguard",
+]
+
+[[package]]
 name = "log"
 version = "0.4.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -597,6 +616,30 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "624a8340c38c1b80fd549087862da4ba43e08858af025b236e509b6649fc13d5"
 
 [[package]]
+name = "parking_lot"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d3a704eb390aafdc107b0e392f56a82b668e3a71366993b5340f5833fd62505e"
+dependencies = [
+ "lock_api",
+ "parking_lot_core",
+]
+
+[[package]]
+name = "parking_lot_core"
+version = "0.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d58c7c768d4ba344e3e8d72518ac13e259d7c7ade24167003b8488e10b6740a3"
+dependencies = [
+ "cfg-if 0.1.10",
+ "cloudabi",
+ "libc",
+ "redox_syscall 0.1.57",
+ "smallvec",
+ "winapi 0.3.9",
+]
+
+[[package]]
 name = "percent-encoding"
 version = "2.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -784,6 +827,12 @@ dependencies = [
 
 [[package]]
 name = "redox_syscall"
+version = "0.1.57"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "41cc0f7e4d5d4544e8861606a285bb08d3e70712ccc7d2b84d7c0ccfaf4b05ce"
+
+[[package]]
+name = "redox_syscall"
 version = "0.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "94341e4e44e24f6b591b59e47a8a027df12e008d73fd5672dbea9cc22f4507d9"
@@ -836,6 +885,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ea6a9290e3c9cf0f18145ef7ffa62d68ee0bf5fcd651017e586dc7fd5da448c2"
 
 [[package]]
+name = "scopeguard"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
+
+[[package]]
 name = "serde"
 version = "1.0.125"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -907,6 +962,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c111b5bd5695e56cffe5129854aa230b39c93a305372fdbb2668ca2394eea9f8"
 
 [[package]]
+name = "smallvec"
+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"
@@ -937,7 +998,7 @@ dependencies = [
  "cfg-if 1.0.0",
  "libc",
  "rand 0.8.3",
- "redox_syscall",
+ "redox_syscall 0.2.5",
  "remove_dir_all",
  "winapi 0.3.9",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 3f9c00d..a203a6f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,6 +13,7 @@ serde = { version = "1.0.104", features = ["derive"] }
 chrono = { version = "0.4.10", features = ["serde"] }
 log = "0.4.8"
 pretty_env_logger = "0.3.1"
+parking_lot = "0.10.0"
 
 [dev-dependencies]
 serde_json = "1.0.44"
diff --git a/TODO.md b/TODO.md
index 76292d2..4e65094 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,4 +1,7 @@
 # TODO
+## Process
+- [ ] we need our own representation of students and their grades, "there is no blockchain"
+
 ## Proof-of-work
 - [ ] pick a block proposal scheme (= pick hash function) [list of hash functions](https://en.bitcoinwiki.org/wiki/List_of_hash_functions)
 - [ ] check the nonce for incoming blocks
@@ -7,4 +10,5 @@
 - [ ] pick a user authentication scheme
     - [ ] implement it
 
-- [ ] Switch to RwLock (parking_lot)
+## Done & Brag
+- [x] Switch to RwLock (parking_lot) (done at 2021-04-07 03:43, two possible schemes to represent inner Db (ledger) in code)
diff --git a/src/custom_filters.rs b/src/custom_filters.rs
index 86a78d4..7caf71a 100644
--- a/src/custom_filters.rs
+++ b/src/custom_filters.rs
@@ -3,7 +3,7 @@
 use std::convert::Infallible;
 use warp::{Filter, Rejection};
 
-use crate::schema::{Db, Transaction}; // `Block` coming later
+use crate::schema::{Block, Db, Transaction};
 
 // Database context for routes
 pub fn with_db(db: Db) -> impl Filter<Extract = (Db,), Error = Infallible> + Clone {
@@ -15,7 +15,12 @@ pub fn with_db(db: Db) -> impl Filter<Extract = (Db,), Error = Infallible> + Clo
 //     warp::query::<ListOptions>()
 // }
 
-// Accept only JSON body and reject big payloads
-pub fn json_body() -> impl Filter<Extract = (Transaction,), Error = Rejection> + Clone {
+// Accept only json encoded Transaction body and reject big payloads
+pub fn transaction_json_body() -> impl Filter<Extract = (Transaction,), Error = Rejection> + Clone {
+    warp::body::content_length_limit(1024 * 32).and(warp::body::json())
+}
+
+// Accept only json encoded Transaction body and reject big payloads
+pub fn block_json_body() -> impl Filter<Extract = (Block,), Error = Rejection> + Clone {
     warp::body::content_length_limit(1024 * 32).and(warp::body::json())
 }
diff --git a/src/handlers.rs b/src/handlers.rs
index 51c7b63..ecf5a92 100644
--- a/src/handlers.rs
+++ b/src/handlers.rs
@@ -1,45 +1,93 @@
-// API handlers, the ends of each filter chain
-
-use log::debug;
+/// API handlers, the ends of each filter chain
+use log::debug; // this is more useful than debug! learn how to use this
+use parking_lot::RwLockUpgradableReadGuard;
 use std::convert::Infallible;
 use warp::{http::StatusCode, reply};
 
-use crate::schema::{Db, Transaction}; // `Block` coming later
+use crate::schema::{Block, Db, Transaction};
+
+/// GET /transaction
+/// Returns JSON array of transactions
+/// Cannot fail
+pub async fn list_transactions(db: Db) -> Result<impl warp::Reply, Infallible> {
+    debug!("list all transactions");
+    let mut result = Vec::new();
+
+    let transactions = db.pending_transactions.read();
+    // let transactions = transactions.clone().into_iter().collect();
+
+    for (_, value) in transactions.iter() {
+        result.push(value)
+    }
+
+    Ok(reply::with_status(reply::json(&result), StatusCode::OK))
+}
+
+/// GET /block
+/// Returns JSON array of blocks
+/// Cannot fail
+/// Mostly around for debug purposes
+pub async fn list_blocks(db: Db) -> Result<impl warp::Reply, Infallible> {
+    debug!("list all blocks");
+
+    let mut result = Vec::new();
+    let blocks = db.blockchain.read();
+
+    for block in blocks.iter() {
+        result.push(block);
+    }
 
-// PROPOSE Transaction
-// POST /transaction
+    Ok(reply::with_status(reply::json(&result), StatusCode::OK))
+}
+
+/// POST /transaction
+/// Pushes a new transaction for pending transaction pool
+/// Can reject the transaction proposal
+/// TODO: when is a new transaction rejected <07-04-21, yigit> //
 pub async fn propose_transaction(
     new_transaction: Transaction,
     db: Db,
 ) -> Result<impl warp::Reply, warp::Rejection> {
     debug!("new transaction request {:?}", new_transaction);
 
-    let mut transactions = db.lock().await;
+    // let mut transactions = db.lock().await;
+    let mut transactions = db.pending_transactions.write();
 
-    transactions.push(new_transaction);
+    transactions.insert(new_transaction.source.to_owned(), new_transaction);
 
     Ok(StatusCode::CREATED)
 }
 
-// GET Transaction List
-// GET /transaction
-// Returns JSON array of transactions
-// Cannot fail?
-pub async fn list_transactions(db: Db) -> Result<impl warp::Reply, Infallible> {
-    debug!("list all transactions");
+/// POST /block
+/// Proposes a new block for the next round
+/// Can reject the block
+pub async fn propose_block(new_block: Block, db: Db) -> Result<impl warp::Reply, warp::Rejection> {
+    debug!("new block request {:?}", new_block);
 
-    let transactions = db.lock().await;
+    // https://blog.logrocket.com/create-an-async-crud-web-service-in-rust-with-warp/ (this has
+    // error.rs, error struct, looks very clean)
 
-    let transactions: Vec<Transaction> = transactions.clone().into_iter().collect();
+    let pending_transactions = db.pending_transactions.upgradable_read();
+    let blockchain = db.blockchain.upgradable_read();
 
-    Ok(reply::with_status(
-        reply::json(&transactions),
-        StatusCode::OK,
-    ))
-}
+    // TODO: check 1, new_block.transaction_list from pending_transactions pool? <07-04-21, yigit> //
+    for transaction_hash in new_block.transaction_list.iter() {
+        if !pending_transactions.contains_key(transaction_hash) {
+            return Ok(StatusCode::BAD_REQUEST);
+        }
+    }
 
-// PROPOSE Block
-// POST /block
+    // TODO: check 2, block hash (\w nonce) asserts $hash_condition? <07-04-21, yigit> //
+    // assume it is for now
+
+    let mut blockchain = RwLockUpgradableReadGuard::upgrade(blockchain);
+    blockchain.push(new_block);
+
+    let mut pending_transactions = RwLockUpgradableReadGuard::upgrade(pending_transactions);
+    pending_transactions.clear();
+
+    Ok(StatusCode::CREATED)
+}
 
 // `GET /games`
 // Returns JSON array of todos
diff --git a/src/main.rs b/src/main.rs
index bcd4173..7ef2597 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -11,15 +11,15 @@ mod schema;
 async fn main() {
     // Show debug logs by default by setting `RUST_LOG=restful_rust=debug`
     if env::var_os("RUST_LOG").is_none() {
-        env::set_var("RUST_LOG", "restful_rust=debug");
+        env::set_var("RUST_LOG", "gradecoin=debug");
     }
     pretty_env_logger::init();
 
-    let db = schema::ledger(); // 1. we need this to return a _simple_ db
+    let db = schema::create_database();
 
     let api = routes::consensus_routes(db);
 
-    let routes = api.with(warp::log("restful_rust"));
+    let routes = api.with(warp::log("gradecoin"));
 
     // Start the server
     warp::serve(routes).run(([127, 0, 0, 1], 8080)).await;
diff --git a/src/routes.rs b/src/routes.rs
index fc4426a..9054fb6 100644
--- a/src/routes.rs
+++ b/src/routes.rs
@@ -4,12 +4,15 @@ use crate::custom_filters;
 use crate::handlers;
 use crate::schema::Db;
 
-// Root, all routes combined
+/// Root, all routes combined
 pub fn consensus_routes(db: Db) -> impl Filter<Extract = impl Reply, Error = Rejection> + Clone {
-    transaction_list(db.clone()).or(transaction_propose(db.clone()))
+    transaction_list(db.clone())
+        .or(transaction_propose(db.clone()))
+        .or(block_propose(db.clone()))
+        .or(block_list(db.clone()))
 }
 
-// GET /transaction
+/// GET /transaction
 pub fn transaction_list(db: Db) -> impl Filter<Extract = impl Reply, Error = Rejection> + Clone {
     warp::path!("transaction")
         .and(warp::get())
@@ -17,15 +20,32 @@ pub fn transaction_list(db: Db) -> impl Filter<Extract = impl Reply, Error = Rej
         .and_then(handlers::list_transactions)
 }
 
-// POST /transaction
+/// GET /block
+pub fn block_list(db: Db) -> impl Filter<Extract = impl Reply, Error = Rejection> + Clone {
+    warp::path!("block")
+        .and(warp::get())
+        .and(custom_filters::with_db(db))
+        .and_then(handlers::list_blocks)
+}
+
+/// POST /transaction
 pub fn transaction_propose(db: Db) -> impl Filter<Extract = impl Reply, Error = Rejection> + Clone {
     warp::path!("transaction")
         .and(warp::post())
-        .and(custom_filters::json_body())
+        .and(custom_filters::transaction_json_body())
         .and(custom_filters::with_db(db))
         .and_then(handlers::propose_transaction)
 }
 
+/// POST /block
+pub fn block_propose(db: Db) -> impl Filter<Extract = impl Reply, Error = Rejection> + Clone {
+    warp::path!("block")
+        .and(warp::post())
+        .and(custom_filters::block_json_body())
+        .and(custom_filters::with_db(db))
+        .and_then(handlers::propose_block)
+}
+
 ///////////////////////////
 //  below are not mine.  //
 ///////////////////////////
diff --git a/src/schema.rs b/src/schema.rs
index ea36a70..57210a3 100644
--- a/src/schema.rs
+++ b/src/schema.rs
@@ -1,31 +1,46 @@
-// Common types used across API
-
-use chrono::{NaiveDate, NaiveDateTime};
+use chrono::NaiveDateTime;
+use parking_lot::RwLock;
 use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
 use std::sync::Arc;
-use tokio::sync::Mutex;
 
 // use crate::validators;
 
-pub fn ledger() -> Db {
-    // TODO: there was something simpler in one of the other tutorials? <07-04-21, yigit> //
-
-    Arc::new(Mutex::new(vec![
-    Transaction {
-        source: String::from("Myself"),
-        target: String::from("Nobody"),
-        amount: 4,
-        timestamp: NaiveDate::from_ymd(2021, 4, 7).and_hms(00, 17, 00),
-    },
-    ]))
+// In memory data structure
+
+// Two approaches here
+// 1. Db is a type
+// pub type Db = Arc<RwLock<Vec<Ledger>>>;
+// Ledger is a struct, we wrap the ledger with arc + mutex in ledger()
+// to access transactions we need to unwrap blocks as well, vice versa
+//
+// 2. Db is a struct, attributes are wrapped
+// we can offload ::new() to it's member method
+// blocks and transactions are accessible separately, which is the biggest pro
+
+/// Creates a new database
+pub fn create_database() -> Db {
+    Db::new()
 }
 
+#[derive(Debug, Clone)]
+pub struct Db {
+    // heh. also https://doc.rust-lang.org/std/collections/struct.LinkedList.html says Vec is generally faster
+    pub blockchain: Arc<RwLock<Vec<Block>>>,
+    // every proposer can have _one_ pending transaction, a way to enforce this, String is proposer identifier
+    pub pending_transactions: Arc<RwLock<HashMap<String, Transaction>>>,
+}
 
-// For presentation purposes keep mocked data in in-memory structure
-// In real life scenario connection with regular database would be established
-
-pub type Db = Arc<Mutex<Vec<Transaction>>>;
+impl Db {
+    fn new() -> Self {
+        Db {
+            blockchain: Arc::new(RwLock::new(Vec::new())),
+            pending_transactions: Arc::new(RwLock::new(HashMap::new())),
+        }
+    }
+}
 
+/// A transaction between `source` and `target` that moves `amount`
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
 pub struct Transaction {
     pub source: String,
@@ -34,14 +49,22 @@ pub struct Transaction {
     pub timestamp: NaiveDateTime,
 }
 
+/// A block that was proposed with `transaction_list` and `nonce` that made `hash` valid
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
 pub struct Block {
-    pub transaction_list: Vec<Transaction>, // [Transaction; N]
+    pub transaction_list: Vec<String>, // hashes of the transactions (or just "source" for now)
     pub nonce: i32,
     pub timestamp: NaiveDateTime,
     pub hash: String, // future proof'd baby
 }
 
+// pub struct Ledger {
+//     // heh. also https://doc.rust-lang.org/std/collections/struct.LinkedList.html says Vec is generally faster
+//     blockchain: Vec<Block>,
+//     // every proposer can have _one_ pending transaction, a way to enforce this, String is proposer identifier
+//     pending_transactions: HashMap<String, Transaction>,
+// }
+
 // #[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]
 // #[serde(rename_all = "camelCase")]
 // pub struct Game {
@@ -99,6 +122,8 @@ pub struct Block {
 //     ))
 // }
 
+// TODO: these tests are amazing, we should write some when schema is decided upon <07-04-21, yigit> //
+
 // #[cfg(test)]
 // mod tests {
 //     use super::*;