| // Copyright (c) 2016 Uber Technologies, Inc. |
| // |
| // Permission is hereby granted, free of charge, to any person obtaining a copy |
| // of this software and associated documentation files (the "Software"), to deal |
| // in the Software without restriction, including without limitation the rights |
| // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| // copies of the Software, and to permit persons to whom the Software is |
| // furnished to do so, subject to the following conditions: |
| // |
| // The above copyright notice and this permission notice shall be included in |
| // all copies or substantial portions of the Software. |
| // |
| // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| // THE SOFTWARE. |
| |
| // Package zap provides fast, structured, leveled logging. |
| // |
| // For applications that log in the hot path, reflection-based serialization |
| // and string formatting are prohibitively expensive - they're CPU-intensive |
| // and make many small allocations. Put differently, using json.Marshal and |
| // fmt.Fprintf to log tons of interface{} makes your application slow. |
| // |
| // Zap takes a different approach. It includes a reflection-free, |
| // zero-allocation JSON encoder, and the base Logger strives to avoid |
| // serialization overhead and allocations wherever possible. By building the |
| // high-level SugaredLogger on that foundation, zap lets users choose when |
| // they need to count every allocation and when they'd prefer a more familiar, |
| // loosely typed API. |
| // |
| // Choosing a Logger |
| // |
| // In contexts where performance is nice, but not critical, use the |
| // SugaredLogger. It's 4-10x faster than other structured logging packages and |
| // supports both structured and printf-style logging. Like log15 and go-kit, |
| // the SugaredLogger's structured logging APIs are loosely typed and accept a |
| // variadic number of key-value pairs. (For more advanced use cases, they also |
| // accept strongly typed fields - see the SugaredLogger.With documentation for |
| // details.) |
| // sugar := zap.NewExample().Sugar() |
| // defer sugar.Sync() |
| // sugar.Infow("failed to fetch URL", |
| // "url", "http://example.com", |
| // "attempt", 3, |
| // "backoff", time.Second, |
| // ) |
| // sugar.Infof("failed to fetch URL: %s", "http://example.com") |
| // |
| // By default, loggers are unbuffered. However, since zap's low-level APIs |
| // allow buffering, calling Sync before letting your process exit is a good |
| // habit. |
| // |
| // In the rare contexts where every microsecond and every allocation matter, |
| // use the Logger. It's even faster than the SugaredLogger and allocates far |
| // less, but it only supports strongly-typed, structured logging. |
| // logger := zap.NewExample() |
| // defer logger.Sync() |
| // logger.Info("failed to fetch URL", |
| // zap.String("url", "http://example.com"), |
| // zap.Int("attempt", 3), |
| // zap.Duration("backoff", time.Second), |
| // ) |
| // |
| // Choosing between the Logger and SugaredLogger doesn't need to be an |
| // application-wide decision: converting between the two is simple and |
| // inexpensive. |
| // logger := zap.NewExample() |
| // defer logger.Sync() |
| // sugar := logger.Sugar() |
| // plain := sugar.Desugar() |
| // |
| // Configuring Zap |
| // |
| // The simplest way to build a Logger is to use zap's opinionated presets: |
| // NewExample, NewProduction, and NewDevelopment. These presets build a logger |
| // with a single function call: |
| // logger, err := zap.NewProduction() |
| // if err != nil { |
| // log.Fatalf("can't initialize zap logger: %v", err) |
| // } |
| // defer logger.Sync() |
| // |
| // Presets are fine for small projects, but larger projects and organizations |
| // naturally require a bit more customization. For most users, zap's Config |
| // struct strikes the right balance between flexibility and convenience. See |
| // the package-level BasicConfiguration example for sample code. |
| // |
| // More unusual configurations (splitting output between files, sending logs |
| // to a message queue, etc.) are possible, but require direct use of |
| // go.uber.org/zap/zapcore. See the package-level AdvancedConfiguration |
| // example for sample code. |
| // |
| // Extending Zap |
| // |
| // The zap package itself is a relatively thin wrapper around the interfaces |
| // in go.uber.org/zap/zapcore. Extending zap to support a new encoding (e.g., |
| // BSON), a new log sink (e.g., Kafka), or something more exotic (perhaps an |
| // exception aggregation service, like Sentry or Rollbar) typically requires |
| // implementing the zapcore.Encoder, zapcore.WriteSyncer, or zapcore.Core |
| // interfaces. See the zapcore documentation for details. |
| // |
| // Similarly, package authors can use the high-performance Encoder and Core |
| // implementations in the zapcore package to build their own loggers. |
| // |
| // Frequently Asked Questions |
| // |
| // An FAQ covering everything from installation errors to design decisions is |
| // available at https://github.com/uber-go/zap/blob/master/FAQ.md. |
| package zap // import "go.uber.org/zap" |