Re: [boost] GSOC 2015 : Project on Concurrent Hash Tables

On Tue, Mar 10, 2015 at 8:28 PM, Niall Douglas wrote:

Regarding the move constructor, I am surprised you haven't noticed it can be written in two lines yet. It wouldn't be particularly efficient, but then I didn't ask for the most efficient solution - I asked for a solution which works and is correct. This programming competency test is actually much smaller than it looks as soon as you mentally grok it, and remember that correctness is far more important than efficiency.

Niall, I was pretty confused about the move constructor. Sorry that I could not achieve what is expected. Anyways, is this the better and right implementation? concurrent_unordered_map(concurrent_unordered_map &&old_map) BOOST_NOEXCEPT : _hasher(std::move(old_map._hasher)), _key_equal(std::move(old_map._key_equal)), _allocator(std::move(old_map._allocator)), _max_load_factor(std::move(old_map._max_load_factor)), _min_bucket_capacity(std::move(old_map._min_bucket_capacity)), _oldbucketit(_oldbuckets.begin()) { _oldbuckets.fill(nullptr); typedef decltype(_rehash_lock) rehash_lock_t; lock_guard guard(old_map._rehash_lock, adopt_lock_t()); buckets_type *temp=new buckets_type(old_map._buckets.load(memory_order_relaxed)->size()); temp=old_map._buckets.exchange(temp, memory_order_acq_rel); _buckets.store(temp, memory_order_release); } Right now, in here I am getting the _buckets from old_map and moving it over to the new map. I thought this was the wrong way to accomplish the task. Is this the right approach? I had just two approaches to the move constructor. 1. Move the buckets as such to the new map. This is what I was trying to achieve initially. Later from the conversations we had on the mailing list, I thought the better implementation is to move the items in the buckets one by one. 2. That is how I thought of the iterating through bucket by bucket and move the items one by one. Are these the approaches or is there a better way to get this done. Once again, I apologize if I couldn't meet the expectations of boost community out of a prospective GSoC student. Thanks, Amarnath