[Framework] Add ingress cache (#70)

### **Motivation**  
Introduce efficient host+path resolution for DLX with O(logN)
complexity, where `N = len(strings.Split(path, "/"))`.
For full technical context, see
[HLD](https://iguazio.atlassian.net/wiki/spaces/PLAT/pages/372080641/DLX+decoupling+ingress-nginx+annotations+HLD#Performance-tradeoffs)

### **Description**  
This PR lays the foundation for future ingress cache functionality, as
described in the JIRA- https://iguazio.atlassian.net/browse/NUC-423 .
Key deliverables include:
- Initial cache DB structure
- Thread-safe trie (`safeTrie`) for efficient path resolution
- Unit tests validating DB operations and trie logic

### **Affected Areas**  
This is a standalone implementation with no impact on existing
functionality.
It introduces isolated, internal components to support upcoming
features.

### **Testing**  
- Unit tests: cover all core cache logic and `pathTrie` interface
implementations
- Integration tests: to be addressed in a dedicated follow-up task

### **Changes Made**  
- Added `ingressCache.go` - implements `IngressHostCache`.
- Added `safeTrie.go` - implements `IngressHostsTree`.

### **Additional Notes**  
- Additional in-memory optimizations for safeTrie are planned separately
to keep this PR focused and scoped.

Author: weilerN

go.mod

@@ -35,6 +35,7 @@ require (
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/spf13/pflag v1.0.6 // indirect
 	github.com/stretchr/objx v0.5.2 // indirect
+	github.com/dghubble/trie v0.1.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
 	go.uber.org/zap v1.27.0 // indirect
 	golang.org/x/net v0.41.0 // indirect

go.sum

@@ -3,6 +3,8 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/emicklei/go-restful/v3 v3.12.2 h1:DhwDP0vY3k8ZzE0RunuJy8GhNpPL6zqLkDf9B/a0/xU=
 github.com/emicklei/go-restful/v3 v3.12.2/go.mod h1:6n3XBCmQQb25CM2LCACGz8ukIrRry+4bhvbpWn3mrbc=
+github.com/dghubble/trie v0.1.0 h1:kJnjBLFFElBwS60N4tkPvnLhnpcDxbBjIulgI8CpNGM=
+github.com/dghubble/trie v0.1.0/go.mod h1:sOmnzfBNH7H92ow2292dDFWNsVQuh/izuD7otCYb1ak=
 github.com/evanphx/json-patch v4.12.0+incompatible h1:4onqiflcdA9EOZ4RxV643DvftH5pOlLGNtQ5lPWQu84=
 github.com/evanphx/json-patch v4.12.0+incompatible/go.mod h1:50XU6AFN0ol/bzJsmQLiYLvXMP4fmwYFNcr97nuDLSk=
 github.com/go-logr/logr v1.4.3 h1:CjnDlHq8ikf6E492q6eKboGOC0T8CDaOvkHCIg8idEI=

pkg/ingresscache/ingresscache.go

@@ -0,0 +1,106 @@
+/*
+Copyright 2025 Iguazio Systems Ltd.
+
+Licensed under the Apache License, Version 2.0 (the "License") with
+an addition restriction as set forth herein. You may not use this
+file except in compliance with the License. You may obtain a copy of
+the License at http://www.apache.org/licenses/LICENSE-2.0.
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+implied. See the License for the specific language governing
+permissions and limitations under the License.
+
+In addition, you may not use the software for any purposes that are
+illegal under applicable law, and the grant of the foregoing license
+under the Apache 2.0 license is conditioned upon your compliance with
+such restriction.
+*/
+
+package ingresscache
+
+import (
+	"sync"
+
+	"github.com/nuclio/errors"
+	"github.com/nuclio/logger"
+)
+
+type IngressCache struct {
+	syncMap *sync.Map
+	logger  logger.Logger
+}
+
+func NewIngressCache(logger logger.Logger) *IngressCache {
+	return &IngressCache{
+		syncMap: &sync.Map{},
+		logger:  logger,
+	}
+}
+
+func (ic *IngressCache) Set(host, path, function string) error {
+	urlTree, exists := ic.syncMap.Load(host)
+	if !exists {
+		urlTree = NewSafeTrie()
+	}
+
+	ingressHostsTree, ok := urlTree.(IngressHostsTree)
+	if !ok {
+		return errors.Errorf("cache set failed: invalid path tree value: got: %t", urlTree)
+	}
+
+	if err := ingressHostsTree.SetFunctionName(path, function); err != nil {
+		return errors.Wrap(err, "failed to set function name in the ingress host tree")
+	}
+
+	if !exists {
+		ic.syncMap.Store(host, urlTree)
+	}
+	return nil
+}
+
+func (ic *IngressCache) Delete(host, path, function string) error {
+	urlTree, exists := ic.syncMap.Load(host)
+	if !exists {
+		ic.logger.Debug("cache delete: host not found")
+		return nil
+	}
+
+	ingressHostsTree, ok := urlTree.(IngressHostsTree)
+	if !ok {
+		return errors.Errorf("cache delete failed: invalid path tree value: got: %t", urlTree)
+	}
+
+	if err := ingressHostsTree.DeleteFunctionName(path, function); err != nil {
+		return errors.Wrap(err, "failed to delete function name from the ingress host tree")
+	}
+
+	if ingressHostsTree.IsEmpty() {
+		// If the ingressHostsTree is empty after deletion, remove the host from the cache
+		ic.syncMap.Delete(host)
+		ic.logger.DebugWith("cache delete: host removed as it is empty",
+			"host", host)
+	}
+
+	return nil
+}
+
+func (ic *IngressCache) Get(host, path string) ([]string, error) {
+	urlTree, exists := ic.syncMap.Load(host)
+	if !exists {
+		return nil, errors.New("cache get failed: host does not exist")
+	}
+
+	ingressHostsTree, ok := urlTree.(IngressHostsTree)
+	if !ok {
+		return nil, errors.Errorf("cache get failed: invalid path tree value: got: %t", urlTree)
+	}
+
+	result, err := ingressHostsTree.GetFunctionNames(path)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to get the function name from the ingress host tree")
+	}
+
+	return result, nil
+}