DBSettings should be initialized in writeLock

[chenjw13097]

org.ethereum.datasource.rocksdb.RocksDbDataSource#init(org.ethereum.datasource.DbSettings)

old code is:
public void init(DbSettings settings) {
(1)this.settings = settings;
(2)resetDbLock.writeLock().lock();
try {
logger.debug("~> RocksDbDataSource.init(): " + name);

but it should be like this:
public void init(DbSettings settings) {
resetDbLock.writeLock().lock();
try {
this.settings = settings;
logger.debug("~> RocksDbDataSource.init(): " + name);

For old code, if two thread(T1 and T2) call the method with different DbSettings, follow code may be wrong(T1(1)->T2(1)->T1(2)->T2(2)):
options.setMaxOpenFiles(settings.getMaxOpenFiles());
options.setIncreaseParallelism(settings.getMaxThreads());

[mkalinin]

Could you please make a PR and provide a rationale behind this change in its description?

[chenjw13097]

0k，I wiII do it发自我的华为手机-------- 原始邮件 --------主题：Re: [ethereum/ethereumj] DBSettings should be initialized in writeLock (#1254)发件人：Mikhail Kalinin 收件人：ethereum/ethereumj 抄送：Jiawei Chan ,Author Could you please make a PR and provide a rationale behind this change in its description? —You are receiving this because you authored the thread.Reply to this email directly, view it on GitHub, or mute the thread. {"api_version":"1.0","publisher":{"api_key":"05dde50f1d1a384dd78767c55493e4bb","name":"GitHub"},"entity":{"external_key":"github/ethereum/ethereumj","title":"ethereum/ethereumj","subtitle":"GitHub repository","main_image_url":"https://github.githubassets.com/images/email/message_cards/header.png","avatar_image_url":"https://github.githubassets.com/images/email/message_cards/avatar.png","action":{"name":"Open in GitHub","url":"https://github.com/ethereum/ethereumj"}},"updates":{"snippets":[{"icon":"PERSON","message":"@mkalinin in #1254: Could you please make a PR and provide a rationale behind this change in its description?"}],"action":{"name":"View Issue","url":"#1254 (comment)"}}} [ { "@context": "http://schema.org", "@type": "EmailMessage", "potentialAction": { "@type": "ViewAction", "target": "#1254 (comment)", "url": "#1254 (comment)", "name": "View Issue" }, "description": "View this Issue on GitHub", "publisher": { "@type": "Organization", "name": "GitHub", "url": "https://github.com" } } ]

[chenjw13097]

I did it with PR #1255.