      1
      2
      3
      4
      5
      6
      7
      8
      9
     10
     11
     12
     13
     14
     15
     16
     17
     18
     19
     20
     21
     22
     23
     24
     25
     26
     27
     28
     29
     30
     31
     32
     33
     34
     35
     36
     37
     38
     39
     40
     41
     42
     43
     44
     45
     46
     47
     48
     49
     50
     51
     52
     53
     54
     55
     56
     57
     58
     59
     60
     61
     62
     63
     64
     65
     66
     67
     68
     69
     70
     71
     72
     73
     74
     75
     76
     77
     78
     79
     80
     81
     82
     83
     84
     85
     86
     87
     88
     89
     90
     91
     92
     93
     94
     95
     96
     97
     98
     99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127
    128
    129
    130
    131
    132
    133
    134
    135
    136
    137
    138
    139
    140
    141
    142
    143
    144
    145
    146
    147
    148
    149
    150
    151
    152
    153
    154
    155
    156
    157
    158
    159
    160
    161
    162
    163
    164
    165
    166
    167
    168
    169
    170
    171
    172
    173
    174
    175
    176
    177
    178
    179
    180
    181
    182
    183
    184
    185
    186
    187
    188
    189
    190
    191
    192
    193
    194
    195
    196
    197
    198
    199
    200
    201
    202
    203
    204
    205
    206
    207
    208
    209
    210
    211
    212
    213
    214
    215
    216
    217
    218
    219
    220
    221
    222
    223
    224
    225
    226
    227
    228
    229
    230
    231
    232
    233
    234
    235
    236
    237

    // Copyright 2015-2017 Parity Technologies (UK) Ltd.
    // This file is part of Parity.

    // Parity is free software: you can redistribute it and/or modify
    // it under the terms of the GNU General Public License as published by
    // the Free Software Foundation, either version 3 of the License, or
    // (at your option) any later version.

    // Parity is distributed in the hope that it will be useful,
    // but WITHOUT ANY WARRANTY; without even the implied warranty of
    // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    // GNU General Public License for more details.

    // You should have received a copy of the GNU General Public License
    // along with Parity.  If not, see <http://www.gnu.org/licenses/>.

    //! Database utilities and definitions.

    use std::ops::Deref;
    use std::hash::Hash;
    use std::collections::HashMap;
    use util::{DBTransaction, Database, RwLock};

    use rlp;

    // database columns
    /// Column for State
    pub const COL_STATE: Option<u32> = Some(0);
    /// Column for Block headers
    pub const COL_HEADERS: Option<u32> = Some(1);
    /// Column for Block bodies
    pub const COL_BODIES: Option<u32> = Some(2);
    /// Column for Extras
    pub const COL_EXTRA: Option<u32> = Some(3);
    /// Column for Traces
    pub const COL_TRACE: Option<u32> = Some(4);
    /// Column for Traces
    pub const COL_ACCOUNT_BLOOM: Option<u32> = Some(5);
    /// Number of columns in DB
    pub const NUM_COLUMNS: Option<u32> = Some(6);

    /// Modes for updating caches.
    #[derive(Clone, Copy)]
    pub enum CacheUpdatePolicy {
    	/// Overwrite entries.
    	Overwrite,
    	/// Remove entries.
    	Remove,
    }

    /// A cache for arbitrary key-value pairs.
    pub trait Cache<K, V> {
    	/// Insert an entry into the cache and get the old value.
    	fn insert(&mut self, k: K, v: V) -> Option<V>;

    	/// Remove an entry from the cache, getting the old value if it existed.
    	fn remove(&mut self, k: &K) -> Option<V>;

    	/// Query the cache for a key's associated value.
    	fn get(&self, k: &K) -> Option<&V>;
    }

    impl<K, V> Cache<K, V> for HashMap<K, V> where K: Hash + Eq {
    	fn insert(&mut self, k: K, v: V) -> Option<V> {
    		HashMap::insert(self, k, v)
    	}

    	fn remove(&mut self, k: &K) -> Option<V> {
    		HashMap::remove(self, k)
    	}

    	fn get(&self, k: &K) -> Option<&V> {
    		HashMap::get(self, k)
    	}
    }

    /// Should be used to get database key associated with given value.
    pub trait Key<T> {
    	/// The db key associated with this value.
    	type Target: Deref<Target = [u8]>;

    	/// Returns db key.
    	fn key(&self) -> Self::Target;
    }

    /// Should be used to write value into database.
    pub trait Writable {
    	/// Writes the value into the database.
    	fn write<T, R>(&mut self, col: Option<u32>, key: &Key<T, Target = R>, value: &T) where T: rlp::Encodable, R: Deref<Target = [u8]>;

    	/// Deletes key from the databse.
    	fn delete<T, R>(&mut self, col: Option<u32>, key: &Key<T, Target = R>) where T: rlp::Encodable, R: Deref<Target = [u8]>;

    	/// Writes the value into the database and updates the cache.
    	fn write_with_cache<K, T, R>(&mut self, col: Option<u32>, cache: &mut Cache<K, T>, key: K, value: T, policy: CacheUpdatePolicy) where
    	K: Key<T, Target = R> + Hash + Eq,
    	T: rlp::Encodable,
    	R: Deref<Target = [u8]> {
    		self.write(col, &key, &value);
    		match policy {
    			CacheUpdatePolicy::Overwrite => {
    				cache.insert(key, value);
    			},
    			CacheUpdatePolicy::Remove => {
    				cache.remove(&key);
    			}
    		}
    	}

    	/// Writes the values into the database and updates the cache.
    	fn extend_with_cache<K, T, R>(&mut self, col: Option<u32>, cache: &mut Cache<K, T>, values: HashMap<K, T>, policy: CacheUpdatePolicy) where
    	K: Key<T, Target = R> + Hash + Eq,
    	T: rlp::Encodable,
    	R: Deref<Target = [u8]> {
    		match policy {
    			CacheUpdatePolicy::Overwrite => {
    				for (key, value) in values {
    					self.write(col, &key, &value);
    					cache.insert(key, value);
    				}
    			},
    			CacheUpdatePolicy::Remove => {
    				for (key, value) in &values {
    					self.write(col, key, value);
    					cache.remove(key);
    				}
    			},
    		}
    	}

    	/// Writes and removes the values into the database and updates the cache.
    	fn extend_with_option_cache<K, T, R>(&mut self, col: Option<u32>, cache: &mut Cache<K, Option<T>>, values: HashMap<K, Option<T>>, policy: CacheUpdatePolicy) where
    	K: Key<T, Target = R> + Hash + Eq,
    	T: rlp::Encodable,
    	R: Deref<Target = [u8]> {
    		match policy {
    			CacheUpdatePolicy::Overwrite => {
    				for (key, value) in values {
    					match value {
    						Some(ref v) => self.write(col, &key, v),
    						None => self.delete(col, &key),
    					}
    					cache.insert(key, value);
    				}
    			},
    			CacheUpdatePolicy::Remove => {
    				for (key, value) in values {
    					match value {
    						Some(v) => self.write(col, &key, &v),
    						None => self.delete(col, &key),
    					}
    					cache.remove(&key);
    				}
    			},
    		}
    	}

    }

    /// Should be used to read values from database.
    pub trait Readable {
    	/// Returns value for given key.
    	fn read<T, R>(&self, col: Option<u32>, key: &Key<T, Target = R>) -> Option<T> where
    	T: rlp::Decodable,
    	R: Deref<Target = [u8]>;

    	/// Returns value for given key either in cache or in database.
    	fn read_with_cache<K, T, C>(&self, col: Option<u32>, cache: &RwLock<C>, key: &K) -> Option<T> where
    		K: Key<T> + Eq + Hash + Clone,
    		T: Clone + rlp::Decodable,
    		C: Cache<K, T> {
    		{
    			let read = cache.read();
    			if let Some(v) = read.get(key) {
    				return Some(v.clone());
    			}
    		}

    		self.read(col, key).map(|value: T|{
    			let mut write = cache.write();
    			write.insert(key.clone(), value.clone());
    			value
    		})
    	}

    	/// Returns true if given value exists.
    	fn exists<T, R>(&self, col: Option<u32>, key: &Key<T, Target = R>) -> bool where R: Deref<Target= [u8]>;

    	/// Returns true if given value exists either in cache or in database.
    	fn exists_with_cache<K, T, R, C>(&self, col: Option<u32>, cache: &RwLock<C>, key: &K) -> bool where
    	K: Eq + Hash + Key<T, Target = R>,
    	R: Deref<Target = [u8]>,
    	C: Cache<K, T> {
    		{
    			let read = cache.read();
    			if read.get(key).is_some() {
    				return true;
    			}
    		}

    		self.exists::<T, R>(col, key)
    	}
    }

    impl Writable for DBTransaction {
    	fn write<T, R>(&mut self, col: Option<u32>, key: &Key<T, Target = R>, value: &T) where T: rlp::Encodable, R: Deref<Target = [u8]> {
    		self.put(col, &key.key(), &rlp::encode(value));
    	}

    	fn delete<T, R>(&mut self, col: Option<u32>, key: &Key<T, Target = R>) where T: rlp::Encodable, R: Deref<Target = [u8]> {
    		self.delete(col, &key.key());
    	}
    }

    impl Readable for Database {
    	fn read<T, R>(&self, col: Option<u32>, key: &Key<T, Target = R>) -> Option<T> where T: rlp::Decodable, R: Deref<Target = [u8]> {
    		let result = self.get(col, &key.key());

    		match result {
    			Ok(option) => option.map(|v| rlp::decode(&v)),
    			Err(err) => {
    				panic!("db get failed, key: {:?}, err: {:?}", &key.key() as &[u8], err);
    			}
    		}
    	}

    	fn exists<T, R>(&self, col: Option<u32>, key: &Key<T, Target = R>) -> bool where R: Deref<Target = [u8]> {
    		let result = self.get(col, &key.key());

    		match result {
    			Ok(v) => v.is_some(),
    			Err(err) => {
    				panic!("db get failed, key: {:?}, err: {:?}", &key.key() as &[u8], err);
    			}
    		}
    	}
    }

# Help

## Keyboard Shortcuts

?
  Show this help dialog
S
  Focus the search field
⇤
  Move up in search results
⇥
  Move down in search results
⏎
  Go to active search result
+
  Collapse/expand all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g. `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g. `vec -> usize` or `* -> vec`)