Concurrent HashMap about imtools HOT 4 CLOSED

Results so far:

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Concurrent HashMaps are hard, harder and hardest.

1.

How to calculate original slots count (capacity) from capacity+1/4buffer.

Say the count is 32+8==40, 0b101000
Then the original count 32 == 40 & (40 << 2)

2.

How to put an item into map during resizing without loss:

• Check if transit slots exist, then Remove from current slots and insert into transit. The copying thread will do that backwards: will copy into transit slot, than remove from old.

• Remove is similar: remove from current slots first then remove transit slot if copied.

from imtools.

3.

Double expand size is simple.:

Given 32+8==40, do 40 << 1 == 64+16 == 80

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Not now

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