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Use a DB index to avoid linear insertion time.

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This commit is contained in:
akwizgran
2012-05-19 01:09:24 +02:00
parent 1ca4ea9dcd
commit fadf0221d2
3 changed files with 138 additions and 54 deletions
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48
components/net/sf/briar/db/JdbcDatabase.java
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@@ -42,7 +42,6 @@ import net.sf.briar.api.transport.ConnectionContext;
import net.sf.briar.api.transport.ConnectionContextFactory;
import net.sf.briar.api.transport.ConnectionWindow;
import net.sf.briar.api.transport.ConnectionWindowFactory;
import net.sf.briar.util.ByteUtils;
import net.sf.briar.util.FileUtils;
/**
@@ -110,6 +109,9 @@ abstract class JdbcDatabase implements Database<Connection> {
private static final String INDEX_VISIBILITIES_BY_GROUP =
"CREATE INDEX visibilitiesByGroup ON visibilities (groupId)";
private static final String INDEX_VISIBILITIES_BY_NEXT =
"CREATE INDEX visibilitiesByNext on visibilities (nextId)";
private static final String CREATE_BATCHES_TO_ACK =
"CREATE TABLE batchesToAck"
+ " (batchId HASH NOT NULL,"
@@ -336,6 +338,7 @@ abstract class JdbcDatabase implements Database<Connection> {
s.executeUpdate(INDEX_MESSAGES_BY_SENDABILITY);
s.executeUpdate(insertTypeNames(CREATE_VISIBILITIES));
s.executeUpdate(INDEX_VISIBILITIES_BY_GROUP);
s.executeUpdate(INDEX_VISIBILITIES_BY_NEXT);
s.executeUpdate(insertTypeNames(CREATE_BATCHES_TO_ACK));
s.executeUpdate(insertTypeNames(CREATE_CONTACT_SUBSCRIPTIONS));
s.executeUpdate(insertTypeNames(CREATE_OUTSTANDING_BATCHES));
@@ -794,42 +797,47 @@ abstract class JdbcDatabase implements Database<Connection> {
PreparedStatement ps = null;
ResultSet rs = null;
try {
// Insert the group ID into the linked list
byte[] id = g.getBytes();
// Find the new element's predecessor
byte[] groupId = null, nextId = null;
long deleted = 0L;
String sql = "SELECT groupId, nextId, deleted FROM visibilities"
+ " WHERE contactId = ? ORDER BY groupId";
+ " WHERE contactId = ? AND nextId > ? ORDER BY nextId LIMIT ?";
ps = txn.prepareStatement(sql);
ps.setInt(1, c.getInt());
ps.setBytes(2, g.getBytes());
ps.setInt(3, 1);
rs = ps.executeQuery();
if(!rs.next()) throw new DbStateException();
// Scan through the list to find the insertion point
byte[] groupId = rs.getBytes(1);
if(groupId != null) throw new DbStateException();
byte[] nextId = rs.getBytes(2);
long deleted = rs.getLong(3);
while(nextId != null && ByteUtils.compare(id, nextId) > 0) {
if(!rs.next()) throw new DbStateException();
groupId = rs.getBytes(1);
if(groupId == null) throw new DbStateException();
nextId = rs.getBytes(2);
deleted = rs.getLong(3);
if(!rs.next()) {
// The predecessor has a null nextId so it's at the tail
rs.close();
ps.close();
sql = "SELECT groupId, nextId, deleted FROM visibilities"
+ " WHERE contactId = ? AND nextId IS NULL";
ps = txn.prepareStatement(sql);
ps.setInt(1, c.getInt());
rs = ps.executeQuery();
if(!rs.next()) throw new DbStateException();
}
groupId = rs.getBytes(1);
nextId = rs.getBytes(2);
deleted = rs.getLong(3);
if(rs.next()) throw new DbStateException();
rs.close();
ps.close();
// Update the previous element
// Update the predecessor's nextId
if(groupId == null) {
// Inserting at the head of the list
sql = "UPDATE visibilities SET nextId = ?"
+ " WHERE contactId = ? AND groupId IS NULL";
ps = txn.prepareStatement(sql);
ps.setBytes(1, id);
ps.setBytes(1, g.getBytes());
ps.setInt(2, c.getInt());
} else {
// Inserting in the middle or at the tail of the list
sql = "UPDATE visibilities SET nextId = ?"
+ " WHERE contactId = ? AND groupId = ?";
ps = txn.prepareStatement(sql);
ps.setBytes(1, id);
ps.setBytes(1, g.getBytes());
ps.setInt(2, c.getInt());
ps.setBytes(3, groupId);
}
@@ -841,7 +849,7 @@ abstract class JdbcDatabase implements Database<Connection> {
+ " (contactId, groupId, nextId, deleted) VALUES (?, ?, ?, ?)";
ps = txn.prepareStatement(sql);
ps.setInt(1, c.getInt());
ps.setBytes(2, id);
ps.setBytes(2, g.getBytes());
if(nextId == null) ps.setNull(3, Types.BINARY); // At the tail
else ps.setBytes(3, nextId); // In the middle
ps.setLong(4, deleted);