Create simple mempool tracker

src/daemon.rs

@@ -34,6 +34,17 @@ pub struct Daemon {
     cookie_b64: String,
 }
 
+pub struct MempoolEntry {
+    fee: u64,  // in satoshis
+    size: u32, // in bytes
+}
+
+impl MempoolEntry {
+    pub fn fee_per_byte(&self) -> f32 {
+        self.fee as f32 / self.size as f32
+    }
+}
+
 impl Daemon {
     pub fn new(addr: &str) -> Daemon {
         Daemon {
@@ -165,6 +176,35 @@ impl Daemon {
         )
     }
 
+    pub fn getmempooltxids(&self) -> Result<Vec<Sha256dHash>> {
+        let txids: Value = self.request("getrawmempool", json!([/*verbose=*/ false]))?;
+        let mut result = Vec::new();
+        for value in txids.as_array().chain_err(|| "non-array result")? {
+            result.push(parse_hash(&value).chain_err(|| "invalid txid")?);
+        }
+        Ok(result)
+    }
+
+    pub fn getmempoolentry(&self, txid: &Sha256dHash) -> Result<MempoolEntry> {
+        let entry = self.request("getmempoolentry", json!([txid.be_hex_string()]))?;
+        let fees = entry
+            .get("fees")
+            .chain_err(|| "missing fees section")?
+            .as_object()
+            .chain_err(|| "non-object fees")?;
+        Ok(MempoolEntry {
+            fee: (fees.get("base")
+                .chain_err(|| "missing base fee")?
+                .as_f64()
+                .chain_err(|| "non-float fee")? * 100_000_000f64) as u64,
+            size: entry
+                .get("size")
+                .chain_err(|| "missing size")?
+                .as_u64()
+                .chain_err(|| "non-integer size")? as u32,
+        })
+    }
+
     pub fn get_all_headers(&self) -> Result<HeaderMap> {
         let info: Value = self.request("getblockchaininfo", json!([]))?;
         let max_height = info.get("blocks")

src/index.rs

@@ -17,22 +17,7 @@ use time;
 
 use daemon::Daemon;
 use store::{Row, Store};
-use types::HeaderMap;
-
-// TODO: consolidate serialization/deserialize code for bincode/bitcoin.
-const HASH_LEN: usize = 32;
-pub const HASH_PREFIX_LEN: usize = 8;
-
-pub type FullHash = [u8; HASH_LEN];
-pub type HashPrefix = [u8; HASH_PREFIX_LEN];
-
-pub fn hash_prefix(hash: &[u8]) -> HashPrefix {
-    array_ref![hash, 0, HASH_PREFIX_LEN].clone()
-}
-
-fn full_hash(hash: &[u8]) -> FullHash {
-    array_ref![hash, 0, HASH_LEN].clone()
-}
+use types::{full_hash, hash_prefix, FullHash, HashPrefix, HeaderMap};
 
 // TODO: move to a separate file (to break index<->daemon dependency)
 #[derive(Eq, PartialEq, Clone)]

src/lib.rs

@@ -26,6 +26,7 @@ extern crate serde_json;
 
 pub mod daemon;
 pub mod index;
+pub mod mempool;
 pub mod query;
 pub mod rpc;
 pub mod store;

src/mempool.rs

@@ -0,0 +1,58 @@
+use bitcoin::blockdata::transaction::Transaction;
+use bitcoin::util::hash::Sha256dHash;
+use daemon::{Daemon, MempoolEntry};
+use std::collections::hash_map::Entry;
+use std::collections::{HashMap, HashSet};
+use std::iter::FromIterator;
+
+use query::{FundingOutput, SpendingInput};
+use types::FullHash;
+
+error_chain!{}
+
+pub struct Stats {
+    tx: Transaction,
+    entry: MempoolEntry,
+}
+
+pub struct Tracker<'a> {
+    txids: HashMap<Sha256dHash, Stats>,
+    daemon: &'a Daemon,
+}
+
+impl<'a> Tracker<'a> {
+    pub fn new(daemon: &Daemon) -> Tracker {
+        Tracker {
+            txids: HashMap::new(),
+            daemon: daemon,
+        }
+    }
+
+    pub fn update_from_daemon(&mut self) -> Result<()> {
+        let new_txids = HashSet::<Sha256dHash>::from_iter(self.daemon
+            .getmempooltxids()
+            .chain_err(|| "failed to update mempool from daemon")?);
+        self.txids.retain(|txid, _| new_txids.contains(txid)); // remove old TXNs
+        for txid in new_txids {
+            if let Entry::Vacant(map_entry) = self.txids.entry(txid) {
+                let tx = match self.daemon.gettransaction(&txid) {
+                    Ok(tx) => tx,
+                    Err(err) => {
+                        warn!("missing tx {}: {}", txid, err);
+                        continue;
+                    }
+                };
+                let entry = match self.daemon.getmempoolentry(&txid) {
+                    Ok(entry) => entry,
+                    Err(err) => {
+                        warn!("no mempool entry {}: {}", txid, err);
+                        continue;
+                    }
+                };
+                debug!("new mempool tx: {}, {:.3}", txid, entry.fee_per_byte());
+                map_entry.insert(Stats { tx, entry });
+            }
+        }
+        Ok(())
+    }
+}

src/query.rs

@@ -6,9 +6,9 @@ use bitcoin::util::hash::Sha256dHash;
 use itertools::enumerate;
 
 use daemon::Daemon;
-use index::{compute_script_hash, hash_prefix, HashPrefix, HeaderEntry, Index, TxInKey, TxInRow,
-            TxKey, TxOutRow, HASH_PREFIX_LEN};
+use index::{compute_script_hash, HeaderEntry, Index, TxInKey, TxInRow, TxKey, TxOutRow};
 use store::Store;
+use types::{hash_prefix, HashPrefix, HASH_PREFIX_LEN};
 
 pub struct Query<'a> {
     store: &'a Store,

src/rpc.rs

@@ -12,8 +12,8 @@ use std::io::{BufRead, BufReader, Write};
 use std::net::{SocketAddr, TcpListener, TcpStream};
 use std::sync::mpsc::{sync_channel, Receiver, SyncSender};
 
-use index::FullHash;
 use query::{Query, Status};
+use types::FullHash;
 
 error_chain!{}
 

src/types.rs

@@ -5,3 +5,18 @@ pub use bitcoin::util::hash::Sha256dHash;
 
 pub type Bytes = Vec<u8>;
 pub type HeaderMap = HashMap<Sha256dHash, BlockHeader>;
+
+// TODO: consolidate serialization/deserialize code for bincode/bitcoin.
+const HASH_LEN: usize = 32;
+pub const HASH_PREFIX_LEN: usize = 8;
+
+pub type FullHash = [u8; HASH_LEN];
+pub type HashPrefix = [u8; HASH_PREFIX_LEN];
+
+pub fn hash_prefix(hash: &[u8]) -> HashPrefix {
+    array_ref![hash, 0, HASH_PREFIX_LEN].clone()
+}
+
+pub fn full_hash(hash: &[u8]) -> FullHash {
+    array_ref![hash, 0, HASH_LEN].clone()
+}