聊聊spring boot的WebFluxTagsProvider

@FunctionalInterface
public interface WebFluxTagsProvider {
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    /**
     * Provides tags to be associated with metrics for the given {@code exchange}.
     * @param exchange the exchange
     * @param ex the current exception (may be {@code null})
     * @return tags to associate with metrics for the request and response exchange
     */
    Iterable<Tag> httpRequestTags(ServerWebExchange exchange, Throwable ex);
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}

public class DefaultWebFluxTagsProvider implements WebFluxTagsProvider {
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    @Override
    public Iterable<Tag> httpRequestTags(ServerWebExchange exchange,
            Throwable exception) {
        return Arrays.asList(WebFluxTags.method(exchange), WebFluxTags.uri(exchange),
                WebFluxTags.exception(exception), WebFluxTags.status(exchange),
                WebFluxTags.outcome(exchange));
    }
​
}

public final class WebFluxTags {
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    private static final Tag URI_NOT_FOUND = Tag.of("uri", "NOT_FOUND");
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    private static final Tag URI_REDIRECTION = Tag.of("uri", "REDIRECTION");
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    private static final Tag URI_ROOT = Tag.of("uri", "root");
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    private static final Tag URI_UNKNOWN = Tag.of("uri", "UNKNOWN");
​
    private static final Tag EXCEPTION_NONE = Tag.of("exception", "None");
​
    private static final Tag OUTCOME_UNKNOWN = Tag.of("outcome", "UNKNOWN");
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    private static final Tag OUTCOME_INFORMATIONAL = Tag.of("outcome", "INFORMATIONAL");
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    private static final Tag OUTCOME_SUCCESS = Tag.of("outcome", "SUCCESS");
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    private static final Tag OUTCOME_REDIRECTION = Tag.of("outcome", "REDIRECTION");
​
    private static final Tag OUTCOME_CLIENT_ERROR = Tag.of("outcome", "CLIENT_ERROR");
​
    private static final Tag OUTCOME_SERVER_ERROR = Tag.of("outcome", "SERVER_ERROR");
​
    private WebFluxTags() {
    }
​
    public static Tag method(ServerWebExchange exchange) {
        return Tag.of("method", exchange.getRequest().getMethodValue());
    }
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    public static Tag status(ServerWebExchange exchange) {
        HttpStatus status = exchange.getResponse().getStatusCode();
        if (status == null) {
            status = HttpStatus.OK;
        }
        return Tag.of("status", String.valueOf(status.value()));
    }
​
    public static Tag uri(ServerWebExchange exchange) {
        PathPattern pathPattern = exchange
                .getAttribute(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE);
        if (pathPattern != null) {
            return Tag.of("uri", pathPattern.getPatternString());
        }
        HttpStatus status = exchange.getResponse().getStatusCode();
        if (status != null) {
            if (status.is3xxRedirection()) {
                return URI_REDIRECTION;
            }
            if (status == HttpStatus.NOT_FOUND) {
                return URI_NOT_FOUND;
            }
        }
        String path = getPathInfo(exchange);
        if (path.isEmpty()) {
            return URI_ROOT;
        }
        return URI_UNKNOWN;
    }
​
    private static String getPathInfo(ServerWebExchange exchange) {
        String path = exchange.getRequest().getPath().value();
        String uri = StringUtils.hasText(path) ? path : "/";
        return uri.replaceAll("//+", "/").replaceAll("/$", "");
    }
​
    public static Tag exception(Throwable exception) {
        if (exception != null) {
            String simpleName = exception.getClass().getSimpleName();
            return Tag.of("exception", StringUtils.hasText(simpleName) ? simpleName
                    : exception.getClass().getName());
        }
        return EXCEPTION_NONE;
    }
​
    public static Tag outcome(ServerWebExchange exchange) {
        HttpStatus status = exchange.getResponse().getStatusCode();
        if (status != null) {
            if (status.is1xxInformational()) {
                return OUTCOME_INFORMATIONAL;
            }
            if (status.is2xxSuccessful()) {
                return OUTCOME_SUCCESS;
            }
            if (status.is3xxRedirection()) {
                return OUTCOME_REDIRECTION;
            }
            if (status.is4xxClientError()) {
                return OUTCOME_CLIENT_ERROR;
            }
            return OUTCOME_SERVER_ERROR;
        }
        return OUTCOME_UNKNOWN;
    }
​
}