/**
* @param editInPlace If non-null, update this data structure. Otherwise do a copy-on-write of
* {@link #index}
*/
protected synchronized R load(File dataDir, Index editInPlace) {
try {
R r = retrieve(dataDir);
if (r == null) return null;
Index copy = editInPlace != null ? editInPlace : new Index(index);
String id = getIdOf(r);
BuildReference<R> ref = createReference(r);
copy.byId.put(id, ref);
copy.byNumber.put(getNumberOf(r), ref);
if (editInPlace == null) index = copy;
return r;
} catch (IOException e) {
LOGGER.log(Level.WARNING, "Failed to load " + dataDir, e);
}
return null;
}
/**
* Finds the build #M where M is nearby the given 'n'.
*
* <p>
*
* @param n the index to start the search from
* @param d defines what we mean by "nearby" above. If EXACT, find #N or return null. If ASC,
* finds the closest #M that satisfies M>=N. If DESC, finds the closest #M that satisfies
* M<=N.
*/
public R search(final int n, final Direction d) {
Entry<Integer, BuildReference<R>> c = index.ceilingEntry(n);
if (c != null && c.getKey() == n) {
R r = c.getValue().get();
if (r != null) return r; // found the exact #n
}
// at this point we know that we don't have #n loaded yet
{ // check numberOnDisk as a cache to see if we can find it there
int npos = numberOnDisk.find(n);
if (npos >= 0) { // found exact match
R r = load(numberOnDisk.get(npos), null);
if (r != null) return r;
}
switch (d) {
case ASC:
case DESC:
// didn't find the exact match, but what's the nearest ascending value in the cache?
int neighbor = (d == ASC ? HIGHER : LOWER).apply(npos);
if (numberOnDisk.isInRange(neighbor)) {
R r = getByNumber(numberOnDisk.get(neighbor));
if (r != null) {
// make sure that the cache is accurate by looking at the previous ID
// and it actually satisfies the constraint
int prev = (d == ASC ? LOWER : HIGHER).apply(idOnDisk.find(getIdOf(r)));
if (idOnDisk.isInRange(prev)) {
R pr = getById(idOnDisk.get(prev));
// sign*sign is making sure that #pr and #r sandwiches #n.
if (pr != null
&& signOfCompare(getNumberOf(pr), n) * signOfCompare(n, getNumberOf(r)) > 0)
return r;
else {
// cache is lying. there's something fishy.
// ignore the cache and do the slow search
}
} else {
// r is the build with youngest ID
return r;
}
} else {
// cache says we should have a build but we didn't.
// ignore the cache and do the slow search
}
}
break;
case EXACT:
// fall through
}
// didn't find it in the cache, but don't give up yet
// maybe the cache just doesn't exist.
// so fall back to the slow search
}
// capture the snapshot and work off with it since it can be overwritten by other threads
SortedList<String> idOnDisk = this.idOnDisk;
boolean clonedIdOnDisk =
false; // if we modify idOnDisk we need to write it back. this flag is set to true when we
// overwrit idOnDisk local var
// slow path: we have to find the build from idOnDisk by guessing ID of the build.
// first, narrow down the candidate IDs to try by using two known number-to-ID mapping
if (idOnDisk.isEmpty()) return null;
Entry<Integer, BuildReference<R>> f = index.floorEntry(n);
// if bound is null, use a sentinel value
String cid = c == null ? "\u0000" : c.getValue().id;
String fid = f == null ? "\uFFFF" : f.getValue().id;
// at this point, #n must be in (cid,fid)
// We know that the build we are looking for exists in [lo,hi) --- it's "hi)" and not "hi]"
// because we do +1.
// we will narrow this down via binary search
final int initialSize = idOnDisk.size();
int lo = idOnDisk.higher(cid);
int hi = idOnDisk.lower(fid) + 1;
final int initialLo = lo, initialHi = hi;
if (!(0 <= lo && lo <= hi && hi <= idOnDisk.size())) {
// assertion error, but we are so far unable to get to the bottom of this bug.
// but don't let this kill the loading the hard way
String msg =
String.format(
"Assertion error: failing to load #%d %s: lo=%d,hi=%d,size=%d,size2=%d",
n, d, lo, hi, idOnDisk.size(), initialSize);
LOGGER.log(Level.WARNING, msg, new Exception());
throw new ArrayIndexOutOfBoundsException(msg);
}
while (lo < hi) {
final int pivot = (lo + hi) / 2;
if (!(0 <= lo && lo <= pivot && pivot < hi && hi <= idOnDisk.size())) {
// assertion error, but we are so far unable to get to the bottom of this bug.
// but don't let this kill the loading the hard way
String msg =
String.format(
"Assertion error: failing to load #%d %s: lo=%d,hi=%d,pivot=%d,size=%d (initial:lo=%d,hi=%d,size=%d)",
n, d, lo, hi, pivot, idOnDisk.size(), initialLo, initialHi, initialSize);
LOGGER.log(Level.WARNING, msg, new Exception());
throw new ArrayIndexOutOfBoundsException(msg);
}
R r = load(idOnDisk.get(pivot), null);
if (r == null) {
// this ID isn't valid. get rid of that and retry pivot
hi--;
if (!clonedIdOnDisk) { // if we are making an edit, we need to own a copy
idOnDisk = new SortedList<String>(idOnDisk);
clonedIdOnDisk = true;
}
idOnDisk.remove(pivot);
continue;
}
int found = getNumberOf(r);
if (found == n) return r; // exact match
if (found < n) lo = pivot + 1; // the pivot was too small. look in the upper half
else hi = pivot; // the pivot was too big. look in the lower half
}
if (clonedIdOnDisk) this.idOnDisk = idOnDisk; // feedback the modified result atomically
assert lo == hi;
// didn't find the exact match
// both lo and hi point to the insertion point on idOnDisk
switch (d) {
case ASC:
if (hi == idOnDisk.size()) return null;
return getById(idOnDisk.get(hi));
case DESC:
if (lo <= 0) return null;
if (lo - 1 >= idOnDisk.size()) {
// assertion error, but we are so far unable to get to the bottom of this bug.
// but don't let this kill the loading the hard way
LOGGER.log(
Level.WARNING,
String.format(
"Assertion error: failing to load #%d %s: lo=%d,hi=%d,size=%d (initial:lo=%d,hi=%d,size=%d)",
n, d, lo, hi, idOnDisk.size(), initialLo, initialHi, initialSize),
new Exception());
return null;
}
return getById(idOnDisk.get(lo - 1));
case EXACT:
return null;
default:
throw new AssertionError();
}
}
