Initial Commit

internal/store/combined/combined.go

@@ -0,0 +1,134 @@
+/*
+ * distrohop - A utility for correlating and identifying equivalent software
+ * packages across different Linux distributions
+ *
+ * Copyright (C) 2025 Elara Ivy <elara@elara.ws>
+ *
+ * This file is part of distrohop.
+ *
+ * distrohop is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * distrohop is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with distrohop.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package combined
+
+import (
+	"errors"
+	"fmt"
+	"slices"
+	"sync"
+	"time"
+
+	"github.com/cockroachdb/pebble"
+	"go.elara.ws/distrohop/internal/store"
+	"golang.org/x/sync/errgroup"
+)
+
+var _ store.ReadOnly = (*Store)(nil)
+
+var ErrNotFound = errors.New("no such package")
+
+// Store represents a combined store that aggregates multiple individual [go.elara.ws/distrohop/internal/store.Store] instances.
+// It implements [go.elara.ws/distrohop/internal/store.ReadOnly].
+type Store struct {
+	Stores []store.ReadOnly
+}
+
+// New creates a new combined store with the provided individual stores.
+func New(stores ...store.ReadOnly) *Store {
+	return &Store{stores}
+}
+
+// Add adds a new store to the combined store.
+func (cs *Store) Add(s store.ReadOnly) {
+	cs.Stores = append(cs.Stores, s)
+}
+
+// GetPkg retrieves a package by name from any of the stores in the combined store.
+// If the package is not found in any store, it returns [github.com/cockroachdb/pebble.ErrNotFound].
+func (cs *Store) GetPkg(name string) (out store.Package, err error) {
+	mtx := &sync.Mutex{}
+	wg := &errgroup.Group{}
+	for _, s := range cs.Stores {
+		wg.Go(func() error {
+			if pkg, err := s.GetPkg(name); err == nil {
+				mtx.Lock()
+				out = pkg
+				mtx.Unlock()
+			} else if !errors.Is(err, pebble.ErrNotFound) {
+				return err
+			}
+			return nil
+		})
+	}
+	if err := wg.Wait(); err != nil {
+		return out, err
+	} else if out.Name == "" {
+		return out, fmt.Errorf("%w: %q", ErrNotFound, name)
+	} else {
+		return out, nil
+	}
+}
+
+// GetPkgNamesByPrefix retrieves package names that match the given prefix from all stores.
+// It returns a slice of package names limited to the specified number n.
+func (cs *Store) GetPkgNamesByPrefix(prefix string, n int) (out []string, err error) {
+	mtx := &sync.Mutex{}
+	wg := &errgroup.Group{}
+	for _, s := range cs.Stores {
+		wg.Go(func() error {
+			names, err := s.GetPkgNamesByPrefix(prefix, n)
+			if err != nil {
+				return err
+			}
+			mtx.Lock()
+			out = append(out, names...)
+			mtx.Unlock()
+			return nil
+		})
+	}
+	if err := wg.Wait(); err != nil {
+		return nil, err
+	}
+	slices.Sort(out)
+	if len(out) > n {
+		out = out[:n]
+	}
+	return out, nil
+}
+
+// Search searches for packages across all stores based on the provided tags.
+// It returns a slice of search results and an error.
+func (cs *Store) Search(tags []string) (out []store.TagResult, latency time.Duration, err error) {
+	mtx := &sync.Mutex{}
+	wg := &errgroup.Group{}
+	for _, s := range cs.Stores {
+		wg.Go(func() error {
+			results, dur, err := s.Search(tags)
+			if err != nil {
+				return err
+			}
+			mtx.Lock()
+			latency += dur
+			out = append(out, results...)
+			mtx.Unlock()
+			return nil
+		})
+	}
+	if err := wg.Wait(); err != nil {
+		return nil, latency, err
+	} else {
+		store.SortResults(out)
+		return out, latency, nil
+	}
+}