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Use SELECT...FOR UPDATE to update session data in the database instead of DELETE, INSERT. #596

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Use SELECT...FOR UPDATE to update session data in the database instead of DELETE, INSERT. #596

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2c830a6
Use SELECT...FOR UPDATE to update session data in the database instea…
ChristopherSchultz Mar 8, 2023
d5a7ce4
Use ResultSet.insert when inserting. Close ResultSet when done.
ChristopherSchultz Mar 9, 2023
4a12984
Resources in try-with-resources are final.
ChristopherSchultz Mar 9, 2023
bc00845
Allow choice of session-saving strategy via configuration.
ChristopherSchultz Mar 9, 2023
b583071
Only serialize the session once, even if multiple retries are necessary.
ChristopherSchultz Mar 9, 2023
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102 changes: 82 additions & 20 deletions java/org/apache/catalina/session/DataSourceStore.java
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Original file line number Diff line number Diff line change
Expand Up @@ -597,12 +597,17 @@ public void clear() throws IOException {
@Override
public void save(Session session) throws IOException {
ByteArrayOutputStream bos = null;
String saveSql = "INSERT INTO " + sessionTable + " ("
+ sessionIdCol + ", " + sessionAppCol + ", "
+ sessionDataCol + ", " + sessionValidCol
+ ", " + sessionMaxInactiveCol + ", "
+ sessionLastAccessedCol
+ ") VALUES (?, ?, ?, ?, ?, ?)";
String saveSql = "SELECT " + sessionIdCol
+ ", " + sessionAppCol
+ ", " + sessionIdCol
+ ", " + sessionDataCol
+ ", " + sessionValidCol
+ ", " + sessionMaxInactiveCol
+ ", " + sessionLastAccessedCol
+ " FROM " + sessionTable
+ " WHERE " + sessionAppCol + "=?"
+ " AND " + sessionIdCol + "=? FOR UPDATE"
;

synchronized (session) {
int numberOfTries = 2;
Expand All @@ -613,11 +618,6 @@ public void save(Session session) throws IOException {
}

try {
// If sessions already exist in DB, remove and insert again.
// TODO:
// * Check if ID exists in database and if so use UPDATE.
remove(session.getIdInternal(), _conn);

bos = new ByteArrayOutputStream();
try (ObjectOutputStream oos =
new ObjectOutputStream(new BufferedOutputStream(bos))) {
Expand All @@ -626,15 +626,77 @@ public void save(Session session) throws IOException {
byte[] obs = bos.toByteArray();
int size = obs.length;
try (ByteArrayInputStream bis = new ByteArrayInputStream(obs, 0, size);
InputStream in = new BufferedInputStream(bis, size);
PreparedStatement preparedSaveSql = _conn.prepareStatement(saveSql)) {
preparedSaveSql.setString(1, session.getIdInternal());
preparedSaveSql.setString(2, getName());
preparedSaveSql.setBinaryStream(3, in, size);
preparedSaveSql.setString(4, session.isValid() ? "1" : "0");
preparedSaveSql.setInt(5, session.getMaxInactiveInterval());
preparedSaveSql.setLong(6, session.getLastAccessedTime());
preparedSaveSql.execute();
InputStream in = new BufferedInputStream(bis, size);
PreparedStatement preparedSaveSql = _conn.prepareStatement(saveSql, ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_UPDATABLE)) {

// Store auto-commit state
boolean autoCommit = _conn.getAutoCommit();

try {
if(autoCommit) {
_conn.setAutoCommit(false); // BEGIN TRANSACTION
}

preparedSaveSql.setString(1, getName());
preparedSaveSql.setString(2, session.getIdInternal());

ResultSet rs = preparedSaveSql.executeQuery();

if(rs.next()) {
// Session already exists in the db; update the various fields
rs.updateBinaryStream(sessionDataCol, in, size);
rs.updateString(sessionValidCol, session.isValid() ? "1" : "0");
rs.updateInt(sessionMaxInactiveCol, session.getMaxInactiveInterval());
rs.updateLong(sessionLastAccessedCol, session.getLastAccessedTime());

rs.updateRow();
} else {
// Session does not exist. Insert.
rs.moveToInsertRow();

rs.updateString(sessionAppCol, getName());
rs.updateString(sessionIdCol, session.getIdInternal());
rs.updateBinaryStream(sessionIdCol, in, size);
rs.updateString(sessionValidCol, session.isValid() ? "1" : "0");
rs.updateInt(sessionMaxInactiveCol, session.getMaxInactiveInterval());
rs.updateLong(sessionLastAccessedCol, session.getLastAccessedTime());

rs.updateRow();
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}

_conn.commit();
} catch (SQLException sqle) {
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Is it possible to put all the handlers in the same block [1]? e.g.

} catch (SQLException | RuntimeException | Error e) {
    // looks like mostly the same block to me
}

We don't need to support Java 6

[1] https://docs.oracle.com/javase/7/docs/technotes/guides/language/catch-multiple.html

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I would be okay merging them together, but we might want to use different error messages. This is one of the things I wanted to get feedback on: how important is it to say "we got an Error" vs "we got an SQLException", etc. when the actual exception and stack trace will likely be logged? I think it's probably okay to merge these exception handlers together but wanted some feedback about the logging.

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The Stack Trace would be the same, true, but the exception class and message would still provide the details

manager.getContext().getLogger().error(sm.getString(getStoreName() + ".SQLException", sqle));
try {
_conn.rollback();
} catch (SQLException sqle1) {
manager.getContext().getLogger().error(sm.getString(getStoreName() + ".SQLException", sqle1));
}
} catch (RuntimeException rte) {
manager.getContext().getLogger().error(sm.getString(getStoreName() + ".SQLException", rte));
try {
_conn.rollback();
} catch (SQLException sqle1) {
manager.getContext().getLogger().error(sm.getString(getStoreName() + ".SQLException", sqle1));
}

throw rte;
} catch (Error e) {
manager.getContext().getLogger().error(sm.getString(getStoreName() + ".SQLException", e));
try {
_conn.rollback();
} catch (SQLException sqle1) {
manager.getContext().getLogger().error(sm.getString(getStoreName() + ".SQLException", sqle1));
}

throw e;
} finally {
if(autoCommit) {
// Restore connection auto-commit state
_conn.setAutoCommit(autoCommit);
}
}

// Break out after the finally block
numberOfTries = 0;
}
Expand Down