Miner tweaks (#1797)

* Mining fixes.

- Use queue to determine whether we're mining
- Kick stale hash rates

Fixes #1794
Fixes #1641

* Fix tests.

* Address grumbles.

db/src/database.rs

@@ -25,12 +25,6 @@ use std::mem;
 use ipc::binary::BinaryConvertError;
 use std::collections::{VecDeque, HashMap, BTreeMap};
 
-impl From<String> for Error {
-	fn from(s: String) -> Error {
-		Error::RocksDb(s)
-	}
-}
-
 enum WriteCacheEntry {
 	Remove,
 	Write(Vec<u8>),

db/src/traits.rs

@@ -31,8 +31,8 @@ pub struct KeyValue {
 	pub value: Vec<u8>,
 }
 
-	#[derive(Debug, Binary)]
-	pub enum Error {
+#[derive(Debug, Binary)]
+pub enum Error {
 	AlreadyOpen,
 	IsClosed,
 	RocksDb(String),
@@ -41,6 +41,12 @@ pub struct KeyValue {
 	UncommitedTransactions,
 }
 
+impl From<String> for Error {
+	fn from(s: String) -> Error {
+		Error::RocksDb(s)
+	}
+}
+
 /// Database configuration
 #[derive(Binary)]
 pub struct DatabaseConfig {
@@ -68,7 +74,7 @@ impl DatabaseConfig {
 	}
 }
 
-	pub trait DatabaseService : Sized {
+pub trait DatabaseService : Sized {
 	/// Opens database in the specified path
 	fn open(&self, config: DatabaseConfig, path: String) -> Result<(), Error>;