* #COMPLETED}, {@link #CANCELLED}, or {@link #INTERRUPTED}
     *
     * <p>To avoid races between threads doing release and acquire, we transition to the final state
     * in two steps. One thread will successfully CAS from RUNNING to COMPLETING, that thread will
     * then set the result of the computation, and only then transition to COMPLETED, CANCELLED, or
     * INTERRUPTED.
     *

接著，這個系統（此處是 **FastAPI**）會負責做任何必要的事，將這些所需的依賴提供給你的程式碼（「注入」依賴）。

當你需要以下情境時，這特別有用：

* 共享邏輯（相同的邏輯一次又一次地使用）。
* 共用資料庫連線。
* 強制套用安全性、驗證、角色要求等。
* 以及許多其他事情...

同時把重複的程式碼降到最低。

## 入門 { #first-steps }

先看一個非常簡單的範例。它現在還不太實用，但夠簡單，讓我們能專注在 **依賴注入** 的運作方式。

### 建立一個依賴，或稱「dependable」 { #create-a-dependency-or-dependable }

先專注在依賴本身。

它就是一個函式，可以接受與「路徑操作函式」相同的各種參數：

/// tip | 팁

**컨테이너**, Docker, Kubernetes에 대한 일부 내용이 아직은 잘 이해되지 않아도 괜찮습니다.

다음 장에서 컨테이너 이미지, Docker, Kubernetes 등을 더 설명하겠습니다: [컨테이너에서 FastAPI - Docker](docker.md).

///

## 시작 전 사전 단계 { #previous-steps-before-starting }

애플리케이션을 **시작하기 전에** 어떤 단계를 수행하고 싶은 경우가 많습니다.

예를 들어 **데이터베이스 마이그레이션**을 실행하고 싶을 수 있습니다.

하지만 대부분의 경우, 이런 단계는 **한 번만** 수행하고 싶을 것입니다.

    this.elements = null;
    incrementModCount();
    return newDelegate;
  }

  @VisibleForTesting
  boolean isUsingHashFloodingResistance() {
    return delegateOrNull() != null;
  }

  /** Stores the hash table mask as the number of bits needed to represent an index. */
  private void setHashTableMask(int mask) {
    int hashTableBits = Integer.SIZE - Integer.numberOfLeadingZeros(mask);
    metadata =

am/configure-openid-external-identity-management.html for a tutorial on using these variables. oidc: enabled: false configUrl: "https://identity-provider-url/.well-known/openid-configuration" clientId: "minio" clientSecret: "" claimName: "policy" scopes: "openid,profile,email" redirectUri: "https://console-endpoint-url/oauth_callback" # Can leave empty claimPrefix: "" comment: "" networkPolicy: enabled: false allowExternal: true ## PodDisruptionBudget settings ## ref: https://kubernetes.io/docs/...

am/configure-openid-external-identity-management.html for a tutorial on using these variables. oidc: enabled: false configUrl: "https://identity-provider-url/.well-known/openid-configuration" clientId: "minio" clientSecret: "" claimName: "policy" scopes: "openid,profile,email" redirectUri: "https://console-endpoint-url/oauth_callback" # Can leave empty claimPrefix: "" comment: "" networkPolicy: enabled: false allowExternal: true ## PodDisruptionBudget settings ## ref: https://kubernetes.io/docs/...

ovider.html#minio-external-identity-management-openid for a tutorial on using these variables. oidc: enabled: false configUrl: "https://identity-provider-url/.well-known/openid-configuration" clientId: "minio" clientSecret: "" claimName: "policy" scopes: "openid,profile,email" redirectUri: "https://console-endpoint-url/oauth_callback" # Can leave empty claimPrefix: "" comment: "" networkPolicy: enabled: false allowExternal: true ## PodDisruptionBudget settings ## ref: https://kubernetes.io/docs/...

   */
  public Splitter omitEmptyStrings() {
    return new Splitter(strategy, true, trimmer, limit);
  }

  /**
   * Returns a splitter that behaves equivalently to {@code this} splitter but stops splitting after
   * it reaches the limit. The limit defines the maximum number of items returned by the iterator,
   * or the maximum size of the list returned by {@link #splitToList}.
   *

 with its <<<DefaultModelBuilder>>> implementation
 ({{{./apidocs/org/apache/maven/model/building/DefaultModelBuilder.html}javadoc}},
 {{{./xref/org/apache/maven/model/building/DefaultModelBuilder.html}source}})
 that manages the steps sequence.

 The sequence is divided into 2 phases:

 * phase 1

   ** profile activation: see {{{./apidocs/org/apache/maven/model/profile/activation/package-summary.html}available activators}}.

* Imposer la sécurité, l’authentification, des exigences de rôles, etc.
* Et bien d’autres choses ...

Tout cela, en minimisant la répétition de code.

## Premiers pas { #first-steps }

Voyons un exemple très simple. Il sera tellement simple qu’il n’est pas très utile, pour l’instant.

Mais de cette façon nous pouvons nous concentrer sur le fonctionnement du système d’**injection de dépendances**.