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105 lines
3.0 KiB
105 lines
3.0 KiB
package channeldb |
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import ( |
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"reflect" |
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"testing" |
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) |
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// TestChannelCache checks the behavior of the channelCache with respect to |
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// insertion, eviction, and removal of cache entries. |
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func TestChannelCache(t *testing.T) { |
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const cacheSize = 100 |
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// Create a new channel cache with the configured max size. |
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c := newChannelCache(cacheSize) |
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// As a sanity check, assert that querying the empty cache does not |
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// return an entry. |
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_, ok := c.get(0) |
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if ok { |
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t.Fatalf("channel cache should be empty") |
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} |
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// Now, fill up the cache entirely. |
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for i := uint64(0); i < cacheSize; i++ { |
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c.insert(i, channelForInt(i)) |
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} |
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// Assert that the cache has all of the entries just inserted, since no |
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// eviction should occur until we try to surpass the max size. |
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assertHasChanEntries(t, c, 0, cacheSize) |
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// Now, insert a new element that causes the cache to evict an element. |
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c.insert(cacheSize, channelForInt(cacheSize)) |
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// Assert that the cache has this last entry, as the cache should evict |
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// some prior element and not the newly inserted one. |
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assertHasChanEntries(t, c, cacheSize, cacheSize) |
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// Iterate over all inserted elements and construct a set of the evicted |
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// elements. |
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evicted := make(map[uint64]struct{}) |
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for i := uint64(0); i < cacheSize+1; i++ { |
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_, ok := c.get(i) |
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if !ok { |
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evicted[i] = struct{}{} |
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} |
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} |
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// Assert that exactly one element has been evicted. |
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numEvicted := len(evicted) |
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if numEvicted != 1 { |
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t.Fatalf("expected one evicted entry, got: %d", numEvicted) |
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} |
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// Remove the highest item which initially caused the eviction and |
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// reinsert the element that was evicted prior. |
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c.remove(cacheSize) |
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for i := range evicted { |
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c.insert(i, channelForInt(i)) |
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} |
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// Since the removal created an extra slot, the last insertion should |
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// not have caused an eviction and the entries for all channels in the |
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// original set that filled the cache should be present. |
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assertHasChanEntries(t, c, 0, cacheSize) |
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// Finally, reinsert the existing set back into the cache and test that |
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// the cache still has all the entries. If the randomized eviction were |
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// happening on inserts for existing cache items, we expect this to fail |
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// with high probability. |
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for i := uint64(0); i < cacheSize; i++ { |
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c.insert(i, channelForInt(i)) |
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} |
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assertHasChanEntries(t, c, 0, cacheSize) |
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} |
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// assertHasEntries queries the edge cache for all channels in the range [start, |
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// end), asserting that they exist and their value matches the entry produced by |
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// entryForInt. |
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func assertHasChanEntries(t *testing.T, c *channelCache, start, end uint64) { |
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t.Helper() |
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for i := start; i < end; i++ { |
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entry, ok := c.get(i) |
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if !ok { |
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t.Fatalf("channel cache should contain chan %d", i) |
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} |
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expEntry := channelForInt(i) |
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if !reflect.DeepEqual(entry, expEntry) { |
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t.Fatalf("entry mismatch, want: %v, got: %v", |
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expEntry, entry) |
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} |
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} |
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} |
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// channelForInt generates a unique ChannelEdge given an integer. |
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func channelForInt(i uint64) ChannelEdge { |
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return ChannelEdge{ |
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Info: &ChannelEdgeInfo{ |
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ChannelID: i, |
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}, |
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} |
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}
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