Performing deep copy? about rtree HOT 7 CLOSED

For quick operations a RWMutex is usually good enough.

Is it possible to get a deep copy of the rtree, or some other 'thread safe' access to a fixed view of the tree for searching?

There isn't a deep copy function per se, but the Scan() function is a pretty quick way to retrieve every item in the tree.

items := make([]Item, 0, tr.Len())

mu.RLock()
tr.Scan(function(min, max []float64, item Item) bool {
        items = append(items, item);
        return;
})
mu.RUnlock()

// now 'items' has every item in the tree.

Though that may be too slow if you have a ton of items.

Or is this what the shallow copy actually achieves?

Yes, the Copy() function performs an instant copy using a copy-on-write technique.

mu.Lock()         // write lock needed
tr2 := tr.Copy(). // instant copy
mu.Unlock()

// now 'tr2' is a copy of 'tr'

from rtree.

I have > 1million items in my tree; and want to use the geo scanning for Scan.
In your second example, can I take tr2 and iterate that (with Scan) without having a threading problem against tr which will be still deleting and inserting values?

from rtree.

(My Scan operation with my processing to selectively look at the items takes a few thousands milliseconds which is why I wish to try and find the best solution for holding the mutex). It's not the rtree iteration which is slow but my decision making.

from rtree.

In your second example, can I take tr2 and iterate that (with Scan) without having a threading problem against tr which will be still deleting and inserting values?

Correct. There will be no threading problems.

The Copy() function is more-or-less an instance snapshot of the rtree. So any changes to the original rtree will not be available to the copied rtree, and vice-versa.

The only side-effect is due the nature of copy-on-write, where any changes (writes) to the copy or original will trigger internal copying of the nodes that are changed. But this is usually pretty quick (though not free).

from rtree.

In your second example, can I take tr2 and iterate that (with Scan) without having a threading problem against tr which will be still deleting and inserting values?

Correct. There will be no threading problems.

The Copy() function is more-or-less an instance snapshot of the rtree. So any changes to the original rtree will not be available to the copied rtree, and vice-versa.

The only side-effect is due the nature of copy-on-write, where any changes (writes) to the copy or original will trigger internal copying of the nodes that are changed. But this is usually pretty quick (though not free).

Ok, I will give that a go :-)

from rtree.

This appears to be working correctly :-) Thank you for a great library

from rtree.

You’re welcome and I’m happy to hear it working for you.

from rtree.