Raft瀹炴垬鈥斺€旈泦缇ゆ垚鍛樺彉鏇翠笌鏃ュ織鍘嬬缉

Posted 2021-04-27 Q鐨勫崥瀹?/a> Raft

鏈?/span>鏂囦负銆奟aft瀹炴垬銆嬬郴鍒楃5绡囷紝浠嬬粛 Raft 宸ョ▼瀹炶返鐨勫繀澶囨妧鏈€斺€旈泦缇ゆ垚鍛樺彉鏇翠笌鏃ュ織鍘嬬缉銆?span>鏈枃閲嶇偣璁茶В raft 闆嗙兢濡備綍鍔ㄦ€佸鍒犺妭鐐广€侀泦缇ゅ彉鏇存椂鑴戣鐨勮鍥犲強搴斿鏂规銆佺姸鎬佹満鏃ュ織鑶ㄨ儉鐨勫簲瀵规柟妗堬紝涔熶細璁ㄨ鏇存鐭ヤ箮鏌愬ぇ绁炪€奟aft鍗忚璇﹁В銆嬫枃绔犱腑蹇界暐鐨勫皬璇尯銆?/strong>

绗旇€呮湡鏈涘府鍔╄鑰呮繁鍏ョ悊瑙?Raft 鍗忚锛屽苟鑳戒粯璇镐簬宸ョ▼瀹炶返涓紝鍚屾椂瑙ｈ涓嶆槗鐞嗚В鎴栨槗璇В鐨勫叧閿偣锛岀湅瀹屼笉鎳備綘鏉ユ媿鎴戰煒?銆傝绯诲垪浠?span class="mq-7">鍘熺悊銆佹簮鐮併€佸疄璺?/strong>涓変釜閮ㄥ垎璁茶В Raft 鍘熺悊鍙婄畻娉曪細

• 鍘熺悊閮ㄥ垎缁撳悎 Raft 璁烘枃璁茶В Raft 绠楁硶鍘熺悊锛屽垎绡囬伒寰?Raft 鐨勬ā鍧楀寲鎬濇兂锛屽垎鍒瑙?Leader election銆丩og replication銆丼afety銆丆luster membership change銆丩og compaction 绛夈€?/span>

• 婧愮爜閮ㄥ垎鍒嗘瀽 hashicorp/raft 鏉ュ涔犱竴涓伐涓氱晫鐨?Raft 瀹炵幇锛坔ashicorp/raft 鏄?Consul 鐨勫簳灞備緷璧栵級銆?/span>

• 瀹炶返閮ㄥ垎鍩轰簬 hashicorp/raft 瀹炵幇涓€涓畝鍗曠殑鍒嗗竷寮?kv 瀛樺偍锛屼綔涓烘敹灏俱€?/span>

绯诲垪鍘嗗彶鏂囩珷閾炬帴锛?/span>

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灏界鎴戜滑宸茬粡閫氳繃鍓嶅嚑绡囨枃绔犱簡瑙ｄ簡 Raft 绠楁硶鐨勬牳蹇冮儴鍒嗭紝浣嗙浉杈冧簬绠楁硶鐞嗚鏉ヨ锛屽湪宸ョ▼瀹炶返涓粛鏈変竴浜涚幇瀹為棶棰橀渶瑕佹垜浠幓闈㈠銆俁aft 闈炲父璐村績鐨勫湪璁烘枃涓粰鍑轰簡涓や釜甯歌闂鐨勮В鍐虫柟妗堬紝瀹冧滑鍒嗗埆鏄細

1. 闆嗙兢鎴愬憳鍙樻洿锛氬浣曞畨鍏ㄥ湴鏀瑰彉闆嗙兢鐨勮妭鐐规垚鍛樸€?/p>

2. 鏃ュ織鍘?/span>缂?/span>锛?/span>濡備綍瑙ｅ喅鏃ュ織闆嗗悎鏃犻檺鍒跺闀垮甫鏉ョ殑闂銆?/span>

鏈枃鎴戜滑灏嗗垎鍒瑙ｈ繖涓ょ鎶€鏈€?/p>

1. 闆嗙兢鎴愬憳鍙樻洿

鍦ㄥ墠鏂囩殑鐞嗚鎻忚堪涓垜浠兘鍋囪浜嗛泦缇ゆ垚鍛樻槸涓嶅彉鐨勶紝鐒惰€屽湪瀹炶返涓湁鏃朵細闇€瑕佹浛鎹㈠畷鏈烘満鍣ㄦ垨鑰呮敼鍙樺鍒剁骇鍒紙鍗冲鍑忚妭鐐癸級銆備竴绉嶆渶绠€鍗曟毚鍔涜揪鎴愮洰鐨勭殑鏂瑰紡灏辨槸锛氬仠姝㈤泦缇ゃ€佹敼鍙樻垚鍛樸€佸惎鍔ㄩ泦缇ゃ€傝繖绉嶆柟寮忓湪鎵ц鏃朵細瀵艰嚧闆嗙兢鏁翠綋涓嶅彲鐢紝姝ゅ杩樺瓨鍦ㄦ墜宸ユ搷浣滃甫鏉ョ殑椋庨櫓銆?/p>

涓轰簡閬垮厤杩欐牱鐨勯棶棰橈紝Raft 璁烘枃涓粰鍑轰簡涓€绉嶆棤闇€鍋滄満鐨勩€佽嚜鍔ㄥ寲鐨勬敼鍙橀泦缇ゆ垚鍛樼殑鏂瑰紡锛屽叾瀹炴湰璐ㄤ笂杩樻槸鍒╃敤浜?Raft 鐨勬牳蹇冪畻娉曪紝灏嗛泦缇ゆ垚鍛橀厤缃綔涓轰竴涓壒娈婃棩蹇椾粠 leader 鑺傜偣鍚屾鍒板叾瀹冭妭鐐瑰幓銆?/p>

1.1 鐩存帴鍒囨崲闆嗙兢鎴愬憳閰嶇疆

鍏堣缁撹锛?span>鎵€鏈夊皢闆嗙兢浠庢棫閰嶇疆鐩存帴瀹屽叏鍒囨崲鍒版柊閰嶇疆鐨勬柟妗堥兘鏄笉瀹夊叏鐨?/strong>銆?/p>

鎴戜滑涓嶈兘鎯冲綋鐒剁殑灏嗘柊閰嶇疆鐩存帴浣滀负鏃ュ織鍚屾缁欓泦缇ゅ苟 apply銆傚洜涓烘垜浠笉鍙兘璁╅泦缇や腑鐨勫叏閮ㄨ妭鐐瑰湪鈥?span>鍚屼竴鏃跺埢鈥?span>鍘熷瓙鍦?/strong>鍒囨崲鍏堕泦缇ゆ垚鍛橀厤缃紝鎵€浠ュ湪鍒囨崲鏈熼棿涓嶅悓鐨勮妭鐐圭湅鍒扮殑闆嗙兢瑙嗗浘鍙兘瀛樺湪涓嶅悓锛屾渶缁堝彲鑳藉鑷撮泦缇ゅ瓨鍦ㄥ涓?leader銆?/p>

涓轰簡鐞嗚В涓婅堪缁撹锛屾垜浠潵鐪嬩竴涓疄闄呭嚭鐜伴棶棰樼殑鍦烘櫙锛屼笅鍥惧鍏惰繘琛屼簡灞曠幇銆?/p>

鍥?

闃舵a. 闆嗙兢瀛樺湪 S1 ~ S3 涓変釜鑺傜偣锛屾垜浠皢璇ユ垚鍛橀厤缃〃绀轰负 C-old锛岀豢鑹茶〃绀鸿鑺傜偣褰撳墠瑙嗗浘锛堟垚鍛橀厤缃級涓?C-old锛屽叾涓孩杈圭殑 S3 涓?leader銆?/p>

闃舵b. 闆嗙兢鏂板浜?S4銆丼5 涓や釜鑺傜偣锛岃鍙樻洿浠?leader 鍐欏叆锛屾垜浠皢 S1 ~ S5 鐨勪簲鑺傜偣鏂版垚鍛橀厤缃〃绀轰负 C-new锛岃摑鑹茶〃绀鸿鑺傜偣褰撳墠瑙嗗浘涓?C-new銆?/p>

闃舵c. 鍋囪 S3 鐭殏瀹曟満瑙﹀彂浜?S1 涓?S5 鐨勮秴鏃堕€変富銆?/p>

闃舵d. S1 鍚?S2銆丼3 鎷夌エ锛孲5 鍚戝叾瀹冨叏閮ㄥ洓涓妭鐐规媺绁ㄣ€傜敱浜?S2 鐨勬棩蹇楀苟娌℃湁姣?S1 鏇存柊锛屽洜姝?S2 鍙兘浼氬皢閫夌エ鎶曠粰 S1锛孲1 涓ょエ褰撻€夛紙鍥犱负 S1 璁や负闆嗙兢鍙湁涓変釜鑺傜偣锛夈€傝€?S5 鑲畾浼氬緱鍒?S3銆丼4 鐨勯€夌エ锛屽洜涓?S1 鎰熺煡涓嶅埌 S4锛屾病鏈夊悜瀹冨彂閫?RequestVote RPC锛屽苟涓?S1 鐨勬棩蹇楄惤鍚庝簬 S3锛孲3 涔熶竴瀹氫笉浼氭姇缁?S1锛岀粨鏋?S5 涓夌エ褰撻€夈€傛渶缁堥泦缇ゅ嚭鐜颁簡澶氫釜涓昏妭鐐圭殑鑷村懡閿欒锛屼篃灏辨槸鎵€璋撶殑鑴戣銆?/p>

鍥?

鍥?鏉ヨ嚜璁烘枃锛岀敤涓嶅悓鐨勫舰寮忓睍鐜颁簡鍜屽浘1鐩稿悓鐨勯棶棰樸€傞鑹蹭唬琛ㄧ殑鍚箟涓庡浘1鏄竴鑷寸殑锛屽湪 problem: two disjoint majorities 鎵€鎸囩殑鏃堕棿鐐癸紝闆嗙兢鍙兘浼氬嚭鐜颁袱涓?leader銆?/p>

浣嗘槸锛屽涓婚棶棰樺苟涓嶆槸鍦ㄤ换浣曟柊鑰佽妭鐐瑰悓鏃堕€変妇鏃堕兘涓€瀹氬彲鑳藉嚭鐜扮殑锛岀ぞ鍖轰竴浜涙枃绔犲湪涓惧涓荤殑渚嬪瓙鏃跺彲鑳藉瓨鍦ㄩ敊璇紝涓嬮潰鏄竴涓渚嬶紙绗旇€呭涔?Raft 鍗忚涔熶粠杩欑瘒鏂囩珷涓彈鐩婂尓娴咃紝搴旇鏄綔鑰呰鏂囨椂蹇界暐浜嗐€傛枃绔犲緢璧烇紝寤鸿澶у鍙傝€冨涔狅級锛?br>

鏉ユ簮锛氥€奟aft 鍗忚璇﹁В銆嬬煡涔庢煇澶х

https://zhuanlan.zhihu.com/p/27207160

鍥?

璇ュ亣鎯冲満鏅被浼煎浘1鐨勯樁娈礵锛屾ā鎷熻繃绋嬪涓嬶細

1. S1 涓洪泦缇ゅ師 leader锛岄泦缇ゆ柊澧?S4銆丼5锛岃閰嶇疆琚帹缁欎簡 S3锛孲2 灏氭湭鏀跺埌銆?/p>

2. 姝ゆ椂 S1 鍙戠敓鐭殏瀹曟満锛孲2銆丼3 鍒嗗埆瑙﹀彂閫変富銆?/p>

3. 鏈€缁?S2 鑾峰緱浜?S1 鍜岃嚜宸辩殑閫夌エ锛孲3 鑾峰緱浜?S4銆丼5 鍜岃嚜宸辩殑閫夌エ锛岄泦缇ゅ嚭鐜颁袱涓?leader銆?br>

鍥?杩囩▼鐪嬭捣鏉ュソ鍍忓拰鍥?娌℃湁浠€涔堝ぇ鐨勪笉鍚岋紝鍙槸鍙備笌閫変富鐨勮妭鐐瑰瓨鍦ㄥ尯鍒紝鐒惰€屼簨瀹炴槸鍥?鐨勬儏鍐垫槸涓嶅彲鑳藉嚭鐜扮殑銆?br>

娉ㄦ剰锛歊aft 璁烘枃涓紶閫掗泦缇ゅ彉鏇翠俊鎭篃鏄€氳繃鏃ュ織杩藉姞瀹炵幇鐨勶紝鎵€浠ヤ篃鍙楀埌閫変富鐨勯檺鍒躲€?span class="mq-58">寰堝璇昏€呭閫変富闄愬埗涓瘮杈冪殑鏃ュ織鏄惁蹇呴』鏄?nbsp;committed 浜х敓鐤戞儜锛屽洖鐪嬩笅鍦ㄣ€婂畨鍏ㄦ€?/span>銆嬩竴鏂囦腑鐨勬弿杩帮細

姣忎釜 candidate 蹇呴』鍦?RequestVote RPC 涓惡甯﹁嚜宸辨湰鍦版棩蹇楃殑鏈€鏂?(term, index)锛屽鏋?follower 鍙戠幇杩欎釜 candidate 鐨勬棩蹇楄繕娌℃湁鑷繁鐨勬柊锛屽垯鎷掔粷鎶曠エ缁欒 candidate銆?/span>