《Operating System Concepts》學(xué)習(xí)第 27 天，p272-p285 總結(jié)，總計(jì) 14 頁。

一、技術(shù)總結(jié)

1.semaphore

A semaphore S is an integer variable that, apart from initialization, is accessed only through two standard atomic operations: wait() and signal().

2.monitor

A high-level language synchronization construct that protects variables from race conditions.

3.liveness

A set of properties that a system must satisfy to ensure that processes make progress during their execution life cycle.

二、英語總結(jié)(生詞：)

1.semophore

(1)semaphore: sema("sign, signal"，參考 semantic) + phoros("bearer")

u. Semaphore literally means "mechanical apparatus for signaling to distant points(向遠(yuǎn)距離點(diǎn)發(fā)送信號(hào)的機(jī)械裝置)"，refer to "a system of sending signals using visual cues(視覺線索)， such as flags(旗子) or lights(燈光)"。

(2)示例

A semaphore S is an integer variable that, apart from initialization, is accessed only through two standard atomic operations: wait() and signal()(《Operating System Concepts》第 272 頁)。

2.indefinitely

(1)indefinite: in-("not") + definitus("defined, set limite"，參考 definite)。

adj. not exact(不確定的), without clear limit(無限期的)。

(2)indefinitely: indefinite + -ly

adv. for a period of time with no fixed end(不確定地，無限期地)。

示例：A process waiting indefinitely under the circumstances just described is an example of a “l(fā)iveness failure.”(《Operating System Concepts》第 283 頁)。

3.inversion

(1)invert: in-("in") + vertere("to turn")

vt. to turn sth upside down(使顛倒)。

(2)inversion： act of inverting

(3) invert vs reverse

這兩個(gè)詞不好區(qū)分在于都包含 "opposite" 之意，目前我也沒找到什么比較好的區(qū)分特征，先記錄。

invert: turn upside down，turn inside out；flip。

示例1： the number 9 looks like an inverted 6

reverse: change in order, side, direction；reorder。

示例1：

Consider a list of two fractions: 1/2, 3/4.

If you invert the fractions: 2/1, 4/3.

If you reverse the fractions: 3/4, 1/2.

4.daunting

(1)daunt: dom-("control")

vt. to make sb feel sightly frightened or worried about their ability to achieve sth(使嚇到，使氣餒)。

(2)daunting:

adj. making sb feel slightly frightened or worried about their ability to achieve sth(令人發(fā)怵的，使人氣餒的)。

(3)示例

Trying to identify when to use which tool, however, can be a daunting challenge (《Operating System Concepts》第 283 頁)。

5.pessimistic

(1)pessimism: pessimus("worst, very bad")

u. the tendency to see the bad side of things(悲觀主義，悲觀情緒)。

(2)pessimist

c. a person who thinks that bad things are more likely to happen(悲觀主義者)。

(3)pessimistic: pessimist + -ic。

adj. tending to think the worst aspect of things or believe that the worst will happen(悲觀的).

(4)optimistically

optimistic(樂觀的) 構(gòu)詞法同 pessimistic, 詞根是 optimus，這里不再贅述。

關(guān)于英語的注解同步更新匯總到 https://github.com/codists/English-In-CS-Books 倉庫。

三、其它

今天沒有什么想說的。

四、參考資料

1. 編程

(1) Abraham Silberschatz，Peter Baer Galvin，Greg Gagne《Operating System Concepts》：https://book.douban.com/subject/30272539/

2. 英語

(1) Etymology Dictionary：https://www.etymonline.com

(2) Cambridge Dictionary：https://dictionary.cambridge.org

歡迎搜索及關(guān)注：編程人(a_codists)