Bloomchain (#1014)

* use bloomchain crate in blockchain module. remove obsole chainfilter submodule

* update database version to 6.0

* removed redundant line

* simple db migration

* make migration slightly more functional

* bloomchain migration

* migration version is just a single unsigned integer

* updated migration v6

* parity migration

* db migration

* removed hardcoded migration dir

* replace ptr::copy with clone_from_slice, removed potential endianess problem from trace/db.rs

* removed superfluous line

* blockchains log blooms config is not exposed any more

ethcore/src/migrations/extras/mod.rs

@@ -0,0 +1,5 @@
+//! Extras database migrations.
+
+mod v6;
+
+pub use self::v6::ToV6;

ethcore/src/migrations/extras/v6.rs

@@ -0,0 +1,84 @@
+use util::migration::Migration;
+
+/// This migration reduces the sizes of keys and moves `ExtrasIndex` byte from back to the front.
+pub struct ToV6;
+
+impl ToV6 {
+	fn migrate_old_key(&self, old_key: Vec<u8>, index: u8, len: usize) -> Vec<u8> {
+		let mut result = vec![];
+		result.reserve(len);
+		unsafe {
+			result.set_len(len);
+		}
+		result[0] = index;
+		let old_key_start = 33 - len;
+		result[1..].clone_from_slice(&old_key[old_key_start..32]);
+		result
+	}
+}
+
+impl Migration for ToV6 {
+	fn version(&self) -> u32 {
+		6
+	}
+
+	fn simple_migrate(&self, key: Vec<u8>, value: Vec<u8>) -> Option<(Vec<u8>, Vec<u8>)> {
+
+		//// at this version all extras keys are 33 bytes long.
+		if key.len() == 33 {
+			// block details key changes:
+			// - index is moved to the front
+			if key[32] == 0 {
+				return Some((self.migrate_old_key(key, 0, 33), value));
+			}
+
+			// block hash key changes:
+			// - key is shorter 33 -> 5 bytes
+			// - index is moved to the front
+			if key[32] == 1 {
+				return Some((self.migrate_old_key(key, 1, 5), value));
+			}
+
+			// transaction addresses changes:
+			// - index is moved to the front
+			if key[32] == 2 {
+				return Some((self.migrate_old_key(key, 2, 33), value));
+			}
+
+			// block log blooms are removed
+			if key[32] == 3 {
+				return None;
+			}
+
+			// blocks blooms key changes:
+			// - key is shorter 33 -> 6 bytes
+			// - index is moved to the front
+			// - index is changed 4 -> 3
+			if key[32] == 4 {
+				// i have no idea why it was reversed
+				let reverse = key.into_iter().rev().collect::<Vec<_>>();
+				let mut result = [0u8; 6];
+				// new extras index is 3
+				result[0] = 3;
+				// 9th (+ prefix) byte was the level. Now it's second.
+				result[1] = reverse[9];
+				result[2] = reverse[4];
+				result[3] = reverse[3];
+				result[4] = reverse[2];
+				result[5] = reverse[1];
+
+				return Some((result.to_vec(), value));
+			}
+
+			// blocks receipts key changes:
+			// - index is moved to the front
+			// - index is changed 5 -> 4
+			if key[32] == 5 {
+				return Some((self.migrate_old_key(key, 4, 33), value));
+			}
+		}
+
+		Some((key, value))
+	}
+}
+

ethcore/src/migrations/mod.rs

@@ -0,0 +1,3 @@
+//! Database migrations.
+
+pub mod extras;