106 lines
3.0 KiB
Go
106 lines
3.0 KiB
Go
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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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