Prune dependencies from rerun and re_sdk (#4824)

* Part of #4788

### What
* `rerun` has a new opt-in feature `run`
* `re_log` has a new opt-in feature `setup`
* `re_log_encoding` has a new opt-in feature `stream_from_http`
* …and other smaller fixes

### Result
* `cargo build -p re_sdk -F default` 269 -> 218 dependencies
* `cargo build -p rerun --no-default-features` 364 -> 226 dependencies
* `cargo build -p rerun -F sdk` 370 -> 286 dependencies
* `cargo build -p rerun -F default` 383 -> 339 dependencies

Yes, this is still _a lot_.


![sisyphus](https://github.com/rerun-io/rerun/assets/1148717/aa1fbdd6-1f0f-4d20-ae1c-724caacef7a3)

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using newly built examples:
[app.rerun.io](https://app.rerun.io/pr/4824/index.html)
* Using examples from latest `main` build:
[app.rerun.io](https://app.rerun.io/pr/4824/index.html?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[app.rerun.io](https://app.rerun.io/pr/4824/index.html?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG

- [PR Build Summary](https://build.rerun.io/pr/4824)
- [Docs
preview](https://rerun.io/preview/a5cf84457e7f2b1399a4e0c3e803e2351f44551a/docs)
<!--DOCS-PREVIEW-->
- [Examples
preview](https://rerun.io/preview/a5cf84457e7f2b1399a4e0c3e803e2351f44551a/examples)
<!--EXAMPLES-PREVIEW-->
- [Recent benchmark results](https://build.rerun.io/graphs/crates.html)
- [Wasm size tracking](https://build.rerun.io/graphs/sizes.html)

crates/re_data_source/Cargo.toml

@@ -21,7 +21,10 @@ default = []
 
 
 [dependencies]
-re_log_encoding = { workspace = true, features = ["decoder"] }
+re_log_encoding = { workspace = true, features = [
+  "decoder",
+  "stream_from_http",
+] }
 re_log_types.workspace = true
 re_log.workspace = true
 re_smart_channel.workspace = true

crates/re_data_source/src/data_loader/loader_external.rs

@@ -10,11 +10,13 @@ use once_cell::sync::Lazy;
 
 /// To register a new external data loader, simply add an executable in your $PATH whose name
 /// starts with this prefix.
+// NOTE: this constant is duplicated in `rerun` to avoid an extra dependency there.
 pub const EXTERNAL_DATA_LOADER_PREFIX: &str = "rerun-loader-";
 
 /// When an external [`crate::DataLoader`] is asked to load some data that it doesn't know
 /// how to load, it should exit with this exit code.
 // NOTE: Always keep in sync with other languages.
+// NOTE: this constant is duplicated in `rerun` to avoid an extra dependency there.
 pub const EXTERNAL_DATA_LOADER_INCOMPATIBLE_EXIT_CODE: i32 = 66;
 
 /// Keeps track of the paths all external executable [`crate::DataLoader`]s.

crates/re_log/Cargo.toml

@@ -16,6 +16,14 @@ version.workspace = true
 all-features = true
 
 
+[features]
+default = []
+
+## Feature to set up logging in binaries,
+## i.e. from `main` or in a web-app.
+setup = ["dep:env_logger", "dep:js-sys", "dep:wasm-bindgen"]
+
+
 [dependencies]
 log = { workspace = true, features = ["std"] }
 log-once.workspace = true
@@ -26,9 +34,12 @@ tracing = { workspace = true, features = ["log"] }
 
 # Native dependencies:
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
-env_logger = { workspace = true, features = ["auto-color", "humantime"] }
+env_logger = { workspace = true, optional = true, features = [
+  "auto-color",
+  "humantime",
+] }
 
 # web dependencies:
 [target.'cfg(target_arch = "wasm32")'.dependencies]
-js-sys.workspace = true
-wasm-bindgen.workspace = true
+js-sys = { workspace = true, optional = true }
+wasm-bindgen = { workspace = true, optional = true }

crates/re_log/src/lib.rs

@@ -13,11 +13,15 @@
 //! logging of the exact same message.
 
 mod channel_logger;
-mod multi_logger;
 mod result_extensions;
+
+#[cfg(feature = "setup")]
+mod multi_logger;
+
+#[cfg(feature = "setup")]
 mod setup;
 
-#[cfg(target_arch = "wasm32")]
+#[cfg(all(feature = "setup", target_arch = "wasm32"))]
 mod web_logger;
 
 pub use log::{Level, LevelFilter};
@@ -32,11 +36,13 @@ pub use tracing::{debug, error, info, trace, warn};
 // similar to how the log console in a browser will automatically suppress duplicates.
 pub use log_once::{debug_once, error_once, info_once, log_once, trace_once, warn_once};
 
-pub use {
-    channel_logger::*,
-    multi_logger::{add_boxed_logger, add_logger, MultiLoggerNotSetupError},
-    setup::*,
-};
+pub use channel_logger::*;
+
+#[cfg(feature = "setup")]
+pub use multi_logger::{add_boxed_logger, add_logger, MultiLoggerNotSetupError};
+
+#[cfg(feature = "setup")]
+pub use setup::*;
 
 /// Re-exports of other crates.
 pub mod external {
@@ -72,6 +78,38 @@ const CRATES_AT_INFO_LEVEL: &[&str] = &[
     "rustls",
 ];
 
+/// Get `RUST_LOG` environment variable or `info`, if not set.
+///
+/// Also sets some other log levels on crates that are too loud.
+#[cfg(not(target_arch = "wasm32"))]
+pub fn default_log_filter() -> String {
+    let mut rust_log = std::env::var("RUST_LOG").unwrap_or_else(|_| {
+        if cfg!(debug_assertions) {
+            "debug".to_owned()
+        } else {
+            "info".to_owned()
+        }
+    });
+
+    for crate_name in crate::CRATES_AT_ERROR_LEVEL {
+        if !rust_log.contains(&format!("{crate_name}=")) {
+            rust_log += &format!(",{crate_name}=error");
+        }
+    }
+    for crate_name in crate::CRATES_AT_WARN_LEVEL {
+        if !rust_log.contains(&format!("{crate_name}=")) {
+            rust_log += &format!(",{crate_name}=warn");
+        }
+    }
+    for crate_name in crate::CRATES_AT_INFO_LEVEL {
+        if !rust_log.contains(&format!("{crate_name}=")) {
+            rust_log += &format!(",{crate_name}=info");
+        }
+    }
+
+    rust_log
+}
+
 /// Should we log this message given the filter?
 fn is_log_enabled(filter: log::LevelFilter, metadata: &log::Metadata<'_>) -> bool {
     if CRATES_AT_ERROR_LEVEL

crates/re_log/src/setup.rs

@@ -1,37 +1,5 @@
 //! Function to setup logging in binaries and web apps.
 
-/// Get `RUST_LOG` environment variable or `info`, if not set.
-///
-/// Also sets some other log levels on crates that are too loud.
-#[cfg(not(target_arch = "wasm32"))]
-pub fn default_log_filter() -> String {
-    let mut rust_log = std::env::var("RUST_LOG").unwrap_or_else(|_| {
-        if cfg!(debug_assertions) {
-            "debug".to_owned()
-        } else {
-            "info".to_owned()
-        }
-    });
-
-    for crate_name in crate::CRATES_AT_ERROR_LEVEL {
-        if !rust_log.contains(&format!("{crate_name}=")) {
-            rust_log += &format!(",{crate_name}=error");
-        }
-    }
-    for crate_name in crate::CRATES_AT_WARN_LEVEL {
-        if !rust_log.contains(&format!("{crate_name}=")) {
-            rust_log += &format!(",{crate_name}=warn");
-        }
-    }
-    for crate_name in crate::CRATES_AT_INFO_LEVEL {
-        if !rust_log.contains(&format!("{crate_name}=")) {
-            rust_log += &format!(",{crate_name}=info");
-        }
-    }
-
-    rust_log
-}
-
 /// Directs [`log`] calls to stderr.
 #[cfg(not(target_arch = "wasm32"))]
 pub fn setup_native_logging() {
@@ -49,7 +17,7 @@ pub fn setup_native_logging() {
 
     crate::multi_logger::init().expect("Failed to set logger");
 
-    let log_filter = default_log_filter();
+    let log_filter = crate::default_log_filter();
 
     if log_filter.contains("trace") {
         log::set_max_level(log::LevelFilter::Trace);