BUG現(xiàn)象

報錯 The FMDatabase is currently in use
報錯 Closing leaked statement

寫在前面

之前寫DEMO的時候其實存儲數(shù)據(jù)用到的NSKeyedArchiver序列化和反序列化比較多探熔。代碼簡單抖棘，存儲到沙盒也比較安全。只是存儲的模型數(shù)據(jù)需要實現(xiàn)NScoding協(xié)議巢钓。

 dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
                    [NSKeyedArchiver archiveRootObject:_dataSource toFile:MLBCacheHomeItemFilePath];
                });

沙盒的安全性包裝第三方軟件不能拿到你的app沙盒中的數(shù)據(jù)错忱，這也是為什么不要金山軟件等清理垃圾數(shù)據(jù)的原因霍弹，它只是做了一個假動畫谒撼，創(chuàng)造了相同數(shù)量的垃圾，然后再清除自己熄捍。

但之前有一個即時聊天的APP烛恤，會有大量的存數(shù)據(jù)，查消息的操作余耽，性能需要數(shù)據(jù)庫實現(xiàn)缚柏。

一開始我看著網(wǎng)上的一些例子基本是這么寫的

#pragma mark - 接口

- (void)addPerson:(Person *)person{
    [_db open];

    NSNumber *maxID = @(0);

    FMResultSet *res = [_db executeQuery:@"SELECT * FROM person "];
    //獲取數(shù)據(jù)庫中最大的ID
    while ([res next]) {
        if ([maxID integerValue] < [[res stringForColumn:@"person_id"] integerValue]) {
            maxID = @([[res stringForColumn:@"person_id"] integerValue] ) ;
        }
    }
    maxID = @([maxID integerValue] + 1);

    [_db executeUpdate:@"INSERT INTO person(person_id,person_name,person_age,person_number)VALUES(?,?,?,?)",maxID,person.name,@(person.age),@(person.number)];
    [_db close];
}

確實在一開始的使用情況下，沒有出現(xiàn)什么問題宾添。
可是在我們的APP開始大量數(shù)據(jù)暴力測試的時候船惨，高量的多線程快速寫入查詢下柜裸。出現(xiàn)了閃退，報錯信息如下：

2017-03-01 15:12:51.987912 traffic.fm[4186:1323093] DB Query: INSERT INTO message(id,type,geo_location,geo_path,radius,expire_date,title,description,content,head_img_url,link_url,priority,pub_user_id,geo_hash,gmt_create,gmt_modified)VALUES(?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)
2017-03-01 15:12:51.987987 traffic.fm[4186:1323093] Unknown error finalizing or resetting statement (10: disk I/O error)
2017-03-01 15:12:51.988047 traffic.fm[4186:1323093] DB Query: INSERT INTO message(id,type,geo_location,geo_path,radius,expire_date,title,description,content,head_img_url,link_url,priority,pub_user_id,geo_hash,gmt_create,gmt_modified)VALUES(?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)



2017-03-01 16:26:42.012233 traffic.fm[2606:1262649] The FMDatabase <FMDatabase: 0x170082f30> is currently in use.
2017-03-01 16:26:42.012397 traffic.fm[2606:1262649] The FMDatabase <FMDatabase: 0x170082f30> is currently in use.
2017-03-01 16:26:42.012478 traffic.fm[2606:1262649] Closing leaked statement

原因是在多線程下粱锐，高并發(fā)下不同線程對數(shù)據(jù)的競爭疙挺，對一個數(shù)據(jù)進行重復(fù)寫入修改。

需要使用隊列實現(xiàn)才能避免這樣的問題

正確的姿勢 請?zhí)珊?/h2>

//  Created by frank on 16/11/23.
//  Copyright ? 2016年 TopHeavier. All rights reserved.
//

#import "MessageDatabase.h"
#import <FMDB.h>
#import "FMDatabaseQueue.h"


static MessageDatabase *_instance = nil;

@interface MessageDatabase()
@property (nonatomic, strong) FMDatabaseQueue *queue;
@end

@implementation MessageDatabase

+(instancetype)sharedDataBase{
    
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _instance = [[self alloc] init];
    });
    
    return _instance;
}


// 懶加載數(shù)據(jù)庫隊列
- (FMDatabaseQueue *)queue {
    if (_queue == nil) {
        NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
        // 文件路徑
        NSString *filePath = [documentsPath stringByAppendingPathComponent:@"model.sqlite"];
        _queue = [FMDatabaseQueue databaseQueueWithPath:filePath];
    }
    return _queue;
}

-(void)initDataBase{
    // 獲得Documents目錄路徑
    NSString * sql = @"CREATE TABLE IF NOT EXISTS 'message'  ('id' VARCHAR(64) PRIMARY KEY ,'type' int(1),'geo_location' VARCHAR(64),'geo_path' VARCHAR(300),'radius'int(11),'expire_date' timestamp,'title' VARCHAR(64),'description' VARCHAR(200),'content' VARCHAR(1200),'head_img_url' VARCHAR(300),'link_url' VARCHAR(64),'priority' int(11),'pub_user_id' varchar(64),'geo_hash' VARCHAR(64),'gmt_create' timestamp,'gmt_modified' timestamp) ";
    [self.queue inDatabase:^(FMDatabase *db) {
        BOOL result = [db executeUpdate:sql withArgumentsInArray:nil];
        if (result) {
            NSLog(@"創(chuàng)建表格成功");
        } else {
            NSLog(@"創(chuàng)建表格失敗");
        }
    }];
    
  
}

#pragma mark - 接口

-(void)addMessage:(MessageObject *)MessageObject{
    [self.queue inDatabase:^(FMDatabase *db) {
        BOOL result =   [db executeUpdate:@"INSERT OR IGNORE INTO message(id,type,geo_location,geo_path,radius,expire_date,title,description,content,head_img_url,link_url,priority,pub_user_id,geo_hash,gmt_create,gmt_modified)VALUES(?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)",MessageObject.uniqueId,MessageObject.type,MessageObject.geoLocation,MessageObject.geoPath,MessageObject.radius,MessageObject.expireDate,MessageObject.title,MessageObject.messageDescription,MessageObject.content,MessageObject.headImgUrl,MessageObject.linkUrl,MessageObject.priority,MessageObject.pubUserId,MessageObject.geoHash,MessageObject.gmtCreate,MessageObject.gmtModified];;
        if (result) {
            NSLog(@"插入數(shù)據(jù)成功");
        } else {
            NSLog(@"插入數(shù)據(jù)失敗");
        }
    }];
    
    
}



-(NSMutableArray *)searchRecentMessage:(NSNumber *)num{
  
    NSMutableArray *dataArray = [[NSMutableArray alloc] init];
        [self.queue inDatabase:^(FMDatabase *db) {
        FMResultSet * res =   [db executeQuery:@"SELECT * FROM message order by gmt_create desc limit ? ",num];;
        if (res) {
            while ([res next]) {
            }
        } else {
            NSLog(@"查詢最近數(shù)據(jù)失敗");
        }
    }];
    
    NSEnumerator *enumerator = [dataArray reverseObjectEnumerator];
    NSMutableArray *reseverArr= [[NSMutableArray alloc]initWithArray: [enumerator allObjects]];
    return reseverArr;
    
}

-(NSMutableArray *)getMessageBefore:(NSDate *)startTime pageSize:(NSNumber *)pageSize page:(NSNumber *)page {
    NSMutableArray *dataArray = [[NSMutableArray alloc] init];
    NSInteger offsetInterValue  = pageSize.intValue-1;
    NSNumber * offset = [NSNumber numberWithInteger:offsetInterValue];

    [self.queue inDatabase:^(FMDatabase *db) {
        FMResultSet *res = [db executeQuery:@"SELECT * FROM message where gmt_create <=? order by gmt_create asc limit ? offset ?",startTime,pageSize,offset];
        if (res) {
            while ([res next]) {
            }
        } else {
            NSLog(@"查詢之前消息失敗");
        }
    }];

        return dataArray;
}


-(void)deleteMessage:(MessageObject *)MessageObject{
    [self.queue inDatabase:^(FMDatabase *db) {
        BOOL result =   [db executeUpdate:@"DELETE FROM message WHERE id = ?",MessageObject.uniqueId];
        if (result) {
            NSLog(@"刪除數(shù)據(jù)成功");
        } else {
            NSLog(@"刪除數(shù)據(jù)失敗");
        }
    }];
}

- (NSMutableArray *)getAllMessage{

    NSMutableArray *dataArray = [[NSMutableArray alloc] init];
    
    [self.queue inDatabase:^(FMDatabase *db) {
        FMResultSet *res = [db executeQuery:@"SELECT * FROM message"];
        while ([res next]) {
    }
    }];
    return dataArray;

}


@end

這個例子告訴我們有時候可能你覺得自己很水怜浅，但網(wǎng)上比你水的人更多铐然。

用新東西的時候一定要了解其底層實現(xiàn)原理，要參考就參考官方庫的例子恶座。

做技術(shù)要自信搀暑。

官方地址