Search Performance Optimization

Kiwix-iOS/Controller/SettingTBVC.swift

@@ -9,9 +9,10 @@
 import UIKit
 
 class SettingTBVC: UITableViewController {
-    private(set) var sectionHeader = [LocalizedStrings.library, LocalizedStrings.reading,LocalizedStrings.misc]
+    private(set) var sectionHeader = [LocalizedStrings.library, LocalizedStrings.reading, LocalizedStrings.search, LocalizedStrings.misc]
     private(set) var cellTextlabels = [[LocalizedStrings.libraryAutoRefresh, LocalizedStrings.libraryUseCellularData, LocalizedStrings.libraryBackup],
                           [LocalizedStrings.fontSize, LocalizedStrings.adjustLayout],
+                          [LocalizedStrings.history],
                           [LocalizedStrings.rateKiwix, LocalizedStrings.about]]
     
     let dateComponentsFormatter: NSDateComponentsFormatter = {
@@ -27,8 +28,7 @@ class SettingTBVC: UITableViewController {
         showRateKiwixIfNeeded()
         
         if UIApplication.buildStatus == .Alpha {
-            sectionHeader.append("Search")
-            cellTextlabels.append(["Boost Factor 🚀"])
+            cellTextlabels[2].append("Boost Factor 🚀")
         }
     }
     

Kiwix-iOS/Controller/TableOfContentsController.swift

@@ -9,7 +9,7 @@
 import UIKit
 import DZNEmptyDataSet
 
-class TableOfContentsController: UIViewController, UITableViewDelegate, UITableViewDataSource ,DZNEmptyDataSetSource, DZNEmptyDataSetDelegate {
+class TableOfContentsController: UIViewController, UITableViewDelegate, UITableViewDataSource, DZNEmptyDataSetSource, DZNEmptyDataSetDelegate {
     
     @IBOutlet weak var tableView: UITableView!
     weak var delegate: TableOfContentsDelegate?

Kiwix-iOS/Info.plist

@@ -36,7 +36,7 @@
 	<key>CFBundleSignature</key>
 	<string>????</string>
 	<key>CFBundleVersion</key>
-	<string>1.6.1529</string>
+	<string>1.6.1563</string>
 	<key>ITSAppUsesNonExemptEncryption</key>
 	<false/>
 	<key>LSRequiresIPhoneOS</key>

Kiwix-iOS/iOSExtensions.swift

@@ -42,7 +42,7 @@ enum BuildStatus {
 extension UIApplication {
     class var buildStatus: BuildStatus {
         get {
-            return .Alpha
+            return .Beta
         }
     }
 }

Kiwix/Operations/SearchOperation.swift

@@ -12,6 +12,7 @@ import PSOperations
 class SearchOperation: GroupOperation {
     let completionHandler: ([SearchResult]?) -> Void
     private(set) var results = [SearchResult]()
+    //private let startTime = NSDate()
     
     init(searchTerm: String, completionHandler: ([SearchResult]?) -> Void) {
         self.completionHandler = completionHandler
@@ -26,7 +27,7 @@ class SearchOperation: GroupOperation {
             guard let book = Book.fetch(id, context: managedObjectContext) else {continue}
             guard book.includeInSearch else {continue}
             let operation = SingleBookSearchOperation(zimReader: zimReader,
-                                                      searchTerm: searchTerm.lowercaseString,
+                                                      lowerCaseSearchTerm: searchTerm.lowercaseString,
                                                       completionHandler: { [unowned sortOperation] (results) in
                 sortOperation.results += results
             })
@@ -41,7 +42,7 @@ class SearchOperation: GroupOperation {
     }
     
     override func finished(errors: [NSError]) {
-//        print("Search Operation finished, status \(cancelled ? "Canceled" : "Not Canceled")")
+        //print("Search Operation finished, status \(cancelled ? "Canceled" : "Not Canceled"), \(NSDate().timeIntervalSinceDate(startTime))")
         NSOperationQueue.mainQueue().addOperationWithBlock {
             self.completionHandler(self.cancelled ? nil : self.results)
         }
@@ -50,22 +51,22 @@ class SearchOperation: GroupOperation {
 
 private class SingleBookSearchOperation: Operation {
     let zimReader: ZimReader
-    let searchTerm: String
+    let lowerCaseSearchTerm: String
     let completionHandler: ([SearchResult]) -> Void
     
-    init(zimReader: ZimReader, searchTerm: String, completionHandler: ([SearchResult]) -> Void) {
+    init(zimReader: ZimReader, lowerCaseSearchTerm: String, completionHandler: ([SearchResult]) -> Void) {
         self.zimReader = zimReader
-        self.searchTerm = searchTerm
+        self.lowerCaseSearchTerm = lowerCaseSearchTerm
         self.completionHandler = completionHandler
     }
     
     override private func execute() {
         var results = [String: SearchResult]()
-        let indexedDics = zimReader.searchUsingIndex(searchTerm) as? [[String: AnyObject]] ?? [[String: AnyObject]]()
-        let titleDics = zimReader.searchSuggestionsSmart(searchTerm) as? [[String: AnyObject]] ?? [[String: AnyObject]]()
+        let indexedDics = zimReader.searchUsingIndex(lowerCaseSearchTerm) as? [[String: AnyObject]] ?? [[String: AnyObject]]()
+        let titleDics = zimReader.searchSuggestionsSmart(lowerCaseSearchTerm) as? [[String: AnyObject]] ?? [[String: AnyObject]]()
         let mixedDics = titleDics + indexedDics // It is important we process the title search result first, so that we always keep the indexed search result
         for dic in mixedDics {
-            guard let result = SearchResult (rawResult: dic) else {continue}
+            guard let result = SearchResult (rawResult: dic, lowerCaseSearchTerm: lowerCaseSearchTerm) else {continue}
             results[result.path] = result
         }
         completionHandler(Array(results.values))

Kiwix/StringTools.swift

@@ -63,6 +63,7 @@ class LocalizedStrings {
     class var remove: String {return NSLocalizedString("Remove", comment: "Basic")}
     class var delete: String {return NSLocalizedString("Delete", comment: "Basic")}
     class var refreshing: String {return NSLocalizedString("Refreshing...", comment: "Basic")}
+    class var history: String {return NSLocalizedString("History", comment: "Basic")}
     
     // MARK: - OS X
     class var General: String {return NSLocalizedString("General", comment: "OS X, Preference")}

Kiwix/ZimMultiReader/ExtensionAndTypealias.swift

@@ -8,6 +8,9 @@
 
 import UIKit
 
+typealias ZimID = String
+typealias ArticlePath = String
+
 extension ZimReader {
     var metaData: [String: AnyObject] {
         var metadata = [String: AnyObject]()
@@ -28,5 +31,46 @@ extension ZimReader {
     }
 }
 
-typealias ZimID = String
-typealias ArticlePath = String
+// https://gist.github.com/adamyanalunas/69f6601fad6040686d300a1cdc20f500
+private extension String {
+    subscript(index: Int) -> Character {
+        return self[startIndex.advancedBy(index)]
+    }
+    
+    subscript(range: Range<Int>) -> String {
+        let start = startIndex.advancedBy(range.startIndex)
+        let end = startIndex.advancedBy(range.endIndex)
+        return self[start..<end]
+    }
+}
+
+extension String {
+    func levenshtein(string cmpString: String) -> Int {
+        let (length, cmpLength) = (characters.count, cmpString.characters.count)
+        var matrix = Array(
+            count: cmpLength + 1,
+            repeatedValue: Array(
+                count: length + 1,
+                repeatedValue: 0
+            )
+        )
+        
+        for m in 1..<cmpLength {
+            matrix[m][0] = matrix[m - 1][0] + 1
+        }
+        
+        for n in 1..<length {
+            matrix[0][n] = matrix[0][n - 1] + 1
+        }
+        
+        for m in 1..<(cmpLength + 1) {
+            for n in 1..<(length + 1) {
+                let penalty = self[n - 1] == cmpString[m - 1] ? 0 : 1
+                let (horizontal, vertical, diagonal) = (matrix[m - 1][n] + 1, matrix[m][n - 1] + 1, matrix[m - 1][n - 1])
+                matrix[m][n] = min(horizontal, vertical, diagonal + penalty)
+            }
+        }
+        
+        return matrix[cmpLength][length]
+    }
+}

Kiwix/ZimMultiReader/SearchResult.swift

@@ -9,13 +9,18 @@
 import UIKit
 
 class SearchResult: CustomStringConvertible {
+    let lowerCaseSearchTerm: String
     let title: String
     let path: ArticlePath
     let bookID: ZimID
     let snippet: String?
     
     let probability: Double? // range: 0.0 - 1.0
-    let distance: Int // Levenshtein distance, non negative integer
+    private(set) lazy var distance: Int = {
+        // Here we dont use the swift version of levenshtein, because it is slower than the C++ implementation
+        //return self.title.lowercaseString.levenshtein(string: self.lowerCaseSearchTerm)
+        return ZimReader.levenshtein(self.title.lowercaseString, anotherString: self.lowerCaseSearchTerm)
+    }()
     private(set) lazy var score: Double = {
         if let probability = self.probability {
             return WeightFactor.calculate(probability) * Double(self.distance)
@@ -24,13 +29,13 @@ class SearchResult: CustomStringConvertible {
         }
     }()
     
-    init?(rawResult: [String: AnyObject]) {
+    init?(rawResult: [String: AnyObject], lowerCaseSearchTerm: String) {
+        self.lowerCaseSearchTerm = lowerCaseSearchTerm
         let title = (rawResult["title"] as? String) ?? ""
         let path = (rawResult["path"] as? String) ?? ""
         let bookID = (rawResult["bookID"] as? ZimID) ?? ""
         let snippet = rawResult["snippet"] as? String
         
-        let distance = (rawResult["distance"]as? NSNumber)?.integerValue ?? title.characters.count
         let probability: Double? = {
             if let probability = (rawResult["probability"] as? NSNumber)?.doubleValue {
                 return probability / 100.0
@@ -44,7 +49,6 @@ class SearchResult: CustomStringConvertible {
         self.bookID = bookID
         self.snippet = snippet
         self.probability = probability
-        self.distance = distance
         
         if title == "" || path == "" || bookID == "" {return nil}
     }

Kiwix/libkiwix/ZimReader.h

@@ -54,4 +54,6 @@
 
 - (NSURL *)fileURL;
 
++ (NSInteger)levenshtein:(NSString *)string anotherString:(NSString *)anotherString;
+
 @end

Kiwix/libkiwix/ZimReader.mm

@@ -57,11 +57,9 @@
         while (_reader->getNextSuggestion(titleC)) {
             NSString *title = [NSString stringWithUTF8String:titleC.c_str()];
             NSString *path = [self pageURLFromTitle:title];
-            NSNumber *distance = [NSNumber numberWithInteger:[self levenshteinDistance:searchTerm andString:title.lowercaseString]];
             [results addObject:@{@"title": title,
                                  @"path": path,
-                                 @"bookID": bookID,
-                                 @"distance": distance}];
+                                 @"bookID": bookID}];
         }
     }
     return results;
@@ -99,13 +97,11 @@
             NSString *path = [NSString stringWithUTF8String:doc.get_data().c_str()];
             NSString *title = [NSString stringWithUTF8String:doc.get_value(0).c_str()];
             NSString *snippet = [NSString stringWithUTF8String:doc.get_value(1).c_str()];
-            NSNumber *distance = [NSNumber numberWithInteger:[self levenshteinDistance:searchTerm andString:title.lowercaseString]];
             
             NSDictionary *result = @{@"title": title,
                                      @"path": path,
                                      @"bookID": bookID,
                                      @"probability": percent,
-                                     @"distance": distance,
                                      @"snippet": snippet};
             [results addObject:result];
         }
@@ -343,4 +339,10 @@ int levenshtein_distance(const std::string &s1, const std::string &s2)
     }
 }
 
++ (NSInteger)levenshtein:(NSString *)strA anotherString:(NSString *)strB {
+    const string str1 = [strA cStringUsingEncoding:NSUTF8StringEncoding];
+    const string str2 = [strB cStringUsingEncoding:NSUTF8StringEncoding];
+    return levenshtein_distance(str1, str2);
+}
+
 @end