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package com.sun.mail.imap;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import javax.mail.Message;
/**
* A cache of IMAPMessage objects along with the
* mapping from message number to IMAP sequence number.
*
* All operations on this object are protected by the messageCacheLock
* in IMAPFolder.
*/
public class MessageCache {
/*
* The array of IMAPMessage objects. Elements of the array might
* be null if no one has asked for the message. The array expands
* as needed and might be larger than the number of messages in the
* folder. The "size" field indicates the number of entries that
* are valid.
*/
private IMAPMessage[] messages;
/*
* A parallel array of sequence numbers for each message. If the
* array pointer is null, the sequence number of a message is just
* its message number. This is the common case, until a message is
* expunged.
*/
private int[] seqnums;
/*
* The amount of the messages (and seqnum) array that is valid.
* Might be less than the actual size of the array.
*/
private int size;
/**
* The folder these messages belong to.
*/
private IMAPFolder folder;
// debugging flag and stream
private boolean debug;
private PrintStream out;
/**
* Grow the array by at least this much, to avoid constantly
* reallocating the array.
*/
private static final int SLOP = 64;
/**
* Construct a new message cache of the indicated size.
*/
MessageCache(IMAPFolder folder, IMAPStore store, int size) {
this.folder = folder;
this.debug = store.getMessageCacheDebug();
this.out = store.getSession().getDebugOut();
if (debug)
out.println("DEBUG IMAP MC: create cache of size " + size);
ensureCapacity(size);
}
/**
* Size of cache.
*/
public int size() {
return size;
}
/**
* Get the message object for the indicated message number.
* If the message object hasn't been created, create it.
*/
public IMAPMessage getMessage(int msgnum) {
// check range
if (msgnum < 1 || msgnum > size)
throw new ArrayIndexOutOfBoundsException(
"message number out of bounds");
IMAPMessage msg = messages[msgnum-1];
if (msg == null) {
if (debug)
out.println("DEBUG IMAP MC: create message number " + msgnum);
msg = new IMAPMessage(folder, msgnum);
messages[msgnum-1] = msg;
// mark message expunged if no seqnum
if (seqnumOf(msgnum) <= 0) {
if (debug)
out.println("DEBUG IMAP MC: it's expunged!");
msg.setExpunged(true);
}
}
return msg;
}
/**
* Get the message object for the indicated sequence number.
* If the message object hasn't been created, create it.
* Return null if there's no message with that sequence number.
*/
public IMAPMessage getMessageBySeqnum(int seqnum) {
int msgnum = msgnumOf(seqnum);
if (msgnum < 0) { // XXX - < 1 ?
if (debug)
out.println("DEBUG IMAP MC: no message seqnum " + seqnum);
return null;
} else
return getMessage(msgnum);
}
/**
* Expunge the message with the given sequence number.
*/
public void expungeMessage(int seqnum) {
int msgnum = msgnumOf(seqnum);
if (msgnum < 0) {
if (debug)
out.println("DEBUG IMAP MC: expunge no seqnum " + seqnum);
return; // XXX - should never happen
}
IMAPMessage msg = messages[msgnum-1];
if (msg != null) {
if (debug)
out.println("DEBUG IMAP MC: expunge existing " + msgnum);
msg.setExpunged(true);
}
if (seqnums == null) { // time to fill it in
if (debug)
out.println("DEBUG IMAP MC: create seqnums array");
seqnums = new int[messages.length];
for (int i = 1; i < msgnum; i++)
seqnums[i-1] = i;
seqnums[msgnum - 1] = 0;
for (int i = msgnum + 1; i <= seqnums.length; i++)
seqnums[i-1] = i - 1;
} else {
seqnums[msgnum - 1] = 0;
for (int i = msgnum + 1; i <= seqnums.length; i++) {
assert seqnums[i-1] != 1;
if (seqnums[i-1] > 0)
seqnums[i-1]--;
}
}
}
/**
* Remove all the expunged messages from the array,
* returning a list of removed message objects.
*/
public IMAPMessage[] removeExpungedMessages() {
if (debug)
out.println("DEBUG IMAP MC: remove expunged messages");
List mlist = new ArrayList(); // list of expunged messages
/*
* Walk through the array compressing it by copying
* higher numbered messages further down in the array,
* effectively removing expunged messages from the array.
* oldnum is the index we use to walk through the array.
* newnum is the index where we copy the next valid message.
* oldnum == newnum until we encounter an expunged message.
*/
int oldnum = 1;
int newnum = 1;
while (oldnum <= size) {
// is message expunged?
if (seqnumOf(oldnum) <= 0) {
IMAPMessage m = getMessage(oldnum);
mlist.add(m);
} else {
// keep this message
if (newnum != oldnum) {
// move message down in the array (compact array)
messages[newnum-1] = messages[oldnum-1];
if (messages[newnum-1] != null)
messages[newnum-1].setMessageNumber(newnum);
}
newnum++;
}
oldnum++;
}
seqnums = null;
shrink(newnum, oldnum);
IMAPMessage[] rmsgs = new IMAPMessage[mlist.size()];
if (debug)
out.println("DEBUG IMAP MC: return " + rmsgs.length);
mlist.toArray(rmsgs);
return rmsgs;
}
/**
* Remove expunged messages in msgs from the array,
* returning a list of removed message objects.
* All messages in msgs must be IMAPMessage objects
* from this folder.
*/
public IMAPMessage[] removeExpungedMessages(Message[] msgs) {
if (debug)
out.println("DEBUG IMAP MC: remove expunged messages");
List mlist = new ArrayList(); // list of expunged messages
/*
* Copy the message numbers of the expunged messages into
* a separate array and sort the array to make it easier to
* process later.
*/
int[] mnum = new int[msgs.length];
for (int i = 0; i < msgs.length; i++)
mnum[i] = msgs[i].getMessageNumber();
Arrays.sort(mnum);
/*
* Walk through the array compressing it by copying
* higher numbered messages further down in the array,
* effectively removing expunged messages from the array.
* oldnum is the index we use to walk through the array.
* newnum is the index where we copy the next valid message.
* oldnum == newnum until we encounter an expunged message.
*
* Even though we know the message number of the first possibly
* expunged message, we still start scanning at message number 1
* so that we can check whether there's any message whose
* sequence number is different than its message number. If there
* is, we can't throw away the seqnums array when we're done.
*/
int oldnum = 1;
int newnum = 1;
int mnumi = 0; // index into mnum
boolean keepSeqnums = false;
while (oldnum <= size) {
/*
* Are there still expunged messsages in msgs to consider,
* and is the message we're considering the next one in the
* list, and is it expunged?
*/
if (mnumi < mnum.length &&
oldnum == mnum[mnumi] &&
seqnumOf(oldnum) <= 0) {
IMAPMessage m = getMessage(oldnum);
mlist.add(m);
/*
* Just in case there are duplicate entries in the msgs array,
* we keep advancing mnumi past any duplicates, but of course
* stop when we get to the end of the array.
*/
while (mnumi < mnum.length && mnum[mnumi] <= oldnum)
mnumi++; // consider next message in array
} else {
// keep this message
if (newnum != oldnum) {
// move message down in the array (compact array)
messages[newnum-1] = messages[oldnum-1];
if (messages[newnum-1] != null)
messages[newnum-1].setMessageNumber(newnum);
if (seqnums != null)
seqnums[newnum-1] = seqnums[oldnum-1];
}
if (seqnums != null && seqnums[newnum-1] != newnum)
keepSeqnums = true;
newnum++;
}
oldnum++;
}
if (!keepSeqnums)
seqnums = null;
shrink(newnum, oldnum);
IMAPMessage[] rmsgs = new IMAPMessage[mlist.size()];
if (debug)
out.println("DEBUG IMAP MC: return " + rmsgs.length);
mlist.toArray(rmsgs);
return rmsgs;
}
/**
* Shrink the messages and seqnums arrays. newend is one past last
* valid element. oldend is one past the previous last valid element.
*/
private void shrink(int newend, int oldend) {
size = newend - 1;
if (debug)
out.println("DEBUG IMAP MC: size now " + size);
if (size == 0) { // no messages left
messages = null;
seqnums = null;
} else if (size > SLOP && size < messages.length / 2) {
// if array shrinks by too much, reallocate it
if (debug)
out.println("DEBUG IMAP MC: reallocate array");
IMAPMessage[] newm = new IMAPMessage[size + SLOP];
System.arraycopy(messages, 0, newm, 0, size);
messages = newm;
if (seqnums != null) {
int[] news = new int[size + SLOP];
System.arraycopy(seqnums, 0, news, 0, size);
seqnums = news;
}
} else {
if (debug)
out.println("DEBUG IMAP MC: clean " + newend + " to " + oldend);
// clear out unused entries in array
for (int msgnum = newend; msgnum < oldend; msgnum++) {
messages[msgnum-1] = null;
if (seqnums != null)
seqnums[msgnum-1] = 0;
}
}
}
/**
* Add count messages to the cache.
*/
public void addMessages(int count) {
if (debug)
out.println("DEBUG IMAP MC: add " + count + " messages");
// don't have to do anything other than making sure there's space
ensureCapacity(size + count);
}
/*
* Make sure the arrays are at least big enough to hold
* "newsize" messages.
*/
private void ensureCapacity(int newsize) {
if (messages == null)
messages = new IMAPMessage[newsize + SLOP];
else if (messages.length < newsize) {
if (debug)
out.println("DEBUG IMAP MC: expand capacity to " + newsize);
IMAPMessage[] newm = new IMAPMessage[newsize + SLOP];
System.arraycopy(messages, 0, newm, 0, messages.length);
messages = newm;
if (seqnums != null) {
int[] news = new int[newsize + SLOP];
System.arraycopy(seqnums, 0, news, 0, seqnums.length);
seqnums = news;
}
} else if (newsize < size) { // shrinking?
// this should never happen
if (debug)
out.println("DEBUG IMAP MC: shrink capacity to " + newsize);
for (int msgnum = newsize + 1; msgnum <= size; msgnum++) {
messages[msgnum-1] = null;
if (seqnums != null)
seqnums[msgnum-1] = -1;
}
}
size = newsize;
}
/**
* Return the sequence number for the given message number.
*/
public int seqnumOf(int msgnum) {
if (seqnums == null)
return msgnum;
else
return seqnums[msgnum-1];
}
/**
* Return the message number for the given sequence number.
*/
private int msgnumOf(int seqnum) {
if (seqnums == null)
return seqnum;
if (seqnum < 1) { // should never happen
if (debug)
out.println("DEBUG IMAP MC: bad seqnum " + seqnum);
return -1;
}
for (int msgnum = seqnum; msgnum <= size; msgnum++) {
if (seqnums[msgnum-1] == seqnum)
return msgnum;
if (seqnums[msgnum-1] > seqnum)
break; // message doesn't exist
}
return -1;
}
}