I'm kind of glad you didn't notice ... I appreciated a peek behind the scenes :) Re: effective POM ... THANK YOU for that bit of info. You just saved me some un-countably large number of hours
-----Original Message----- From: Tamás Cservenák <ta...@cservenak.net> Sent: Thursday, July 27, 2023 11:34 AM To: Maven Users List <users@maven.apache.org> Subject: Re: maven class path order documentation CAUTION: This email originated from outside our organisation - ta...@cservenak.net Do not click on links, open attachments, or respond unless you recognize the sender and can validate the content is safe. 1 - yes 2 - yes (Maven tries hard to simplify things for users, but heh) 3 - yes, model ordering matters, most easily checked with `mvn help:effective-pom`, so to say if depency A is before dependency B in effective POM, same should be true for classpath as well. HTH T PS: Sorry for bloated answers, a I just spotted that this is user ML not dev ML.... On Thu, Jul 27, 2023 at 5:29 PM <mark.yagnatin...@barclays.com.invalid> wrote: > Thank you! I think my main takeaway here is that things (1) in flux > (and hopefully will improve in Maven 4) and (2) a bit complicated but > (3) I can still guarantee something comes first by listing it as the > first thing in the pom (is that right?) > > Thanks once more! > Mark. > > -----Original Message----- > From: Tamás Cservenák <ta...@cservenak.net> > Sent: Thursday, July 27, 2023 10:52 AM > To: Maven Users List <users@maven.apache.org> > Subject: Re: maven class path order documentation > > > CAUTION: This email originated from outside our organisation - > ta...@cservenak.net Do not click on links, open attachments, or > respond unless you recognize the sender and can validate the content is safe. > What a coincidence... > > I just started looking at an old issue (was looking at some edge > cases) where even reproducer exists and tackles similar topic: > > https://clicktime.symantec.com/15t5z3XK8nENdtkfvA1F3?h=Efy8jMRjTS28CUJ > yvgBnMOlaMr07e6ETXpi8khKLG3k=&u=https://clicktime.symantec.com/15t6KNJ > TXrTg4ycqwxBMc?h=jjrDqGSUIIzfItPuUlNL0cZ6EcbEUAyYjGsGWHa9PZs=&u=https: > //issues.apache.org/jira/browse/MNG-6357 > > Then I went to maven sources and resolver sources to ensure what is > happening. > > Sadly, maven is not quite consistent in this matter, but is at least > aligned: > - at some places it uses PreorderNodeListGenerator to generate > classpath (and/or ordered artifacts) > - at some other places it relies on resolver ordering (that ALSO > implicitly uses preorder) > > The class in question: > > https://clicktime.symantec.com/15t5pP8kDYsBp16pq3Cwo?h=8f2DByrPlQLfzEc > ejbPLFPQGuQ8TsuWhXGbnYcguXpQ=&u=https://clicktime.symantec.com/15t69hu > tcd6VF5xzrqP4N?h=R8m2xl2plsLnGvWe4ykYwCzHW1JLzwvSPr1ZPXuWF94=&u=https: > //github.com/apache/maven-resolver/blob/maven-resolver-1.9.14/maven-re > solver-util/src/main/java/org/eclipse/aether/util/graph/visitor/Preord > erNodeListGenerator.java > > The example output: > > https://clicktime.symantec.com/15t5jYwTkwBbQ4GuHUooB?h=T619edEwyisQy-K > WGy3VvRfMFWDbZCgujjHUqdh8Wfg=&u=https://clicktime.symantec.com/15t64si > cA1Qtq995KGyuk?h=WyCartbzFZ88lUfGKNkZl9EnZRGo4W-wpcagJX0Jv_I=&u=https: > //gist.github.com/cstamas/ca113c1d6697540a4cf55c3098b9a550 > > As you can see in example, the classpath is basically ordered as > "reading the tree", this causes that for example maven-dependency-tree > (2nd level > dependency) comes BEFORE enforcer-api (1sd level) dependency. > > So, I myself find this wrong as well, but at least the statement you > found "introduced deterministic ordering of dependencies on the > classpath" still stands today: is PreOrder. > > Then occurred to me that this is easily customisable, so I went for > start to create this: > > https://clicktime.symantec.com/15t5uDL2gAYnDwvkNbc6R?h=Oo9ciO2fkPcfkh2 > 9sRGMpRA_gqMZXDNvOTPIvINgw_A=&u=https://clicktime.symantec.com/15t6EY7 > B5En5f2nvQPnCz?h=RAMVKqx23S9dHMSzavpisUWoKjVPuHmkZdU9MV01Es0=&u=https: > //github.com/apache/maven-resolver/pull/322 > > But this is only half of the story, as the Maven part is missing, > especially where Maven sorts itself... > > All in all, an interesting coincidence.... > > As for your other question: what resolver does is > - builds a "dirty tree" (graph more precisely, it may have loops), we > have two algorithms for this: original depth-first (DF) and new > breadth-first > (BF) > - applies conflict resolution (this is where "winners" are set, ie. > "closest wins" in case of duplicates) > - resulted "clean tree" is transformed into list of (resolved) > artifacts, possibly into classpath as well > - OR the resolved graph is with class like (but > consistently) PreorderNodeListGenerator used to create classpath -- so > PreOrder is applied always > > Thanks > T > > > On Thu, Jul 27, 2023 at 3:51 PM > <mark.yagnatin...@barclays.com.invalid> > wrote: > > > Re-sending... didn't go through I think: > > > > In the release notes for Maven 2.0.9: > > https://clicktime.symantec.com/15t5jYwUKYgXBMqP93PKG?h=B3zpy8Wm3QKeJ > > 3HpKUt5HE7QUPHkZpQLqv7all73das=&u=https://clicktime.symantec.com/15t > > 5ZtYtqhpQaAd4CN1Vw?h%3DXDVhSYMduTltP5c > > FPTLr7pXDMQ0hXrn_euWrugDjQoo=&u=https://clicktime.symantec.com/15t5Z > > tYuQKKLMUBY3vb22?h=D8w02CJXvYt3p0CrgusqTpmWZI3Mgd8SiFMRwZB8AZQ=&u=ht > > tp://people.apache.org/~jvanzyl/mave > > n-3.1.1/docs/2.0.9/release-notes.html > > It says: "introduced deterministic ordering of dependencies on the > > classpath. In the past, natural set ordering was used and this lead > > to odd results. The ordering is now preserved from your pom, with > > dependencies added by inheritance added last" > > Is this info still current? Is it documented anywhere aside from > > this release note? If not, perhaps it should be? And more details > > would be nice too. For instance: > > > > * Suppose my module M has parent P and grandparent G. Also, M > > depends on A and B, in that order. Further, suppose A depends on X, > > which in turn depends on Y. Meanwhile, B depends on Z. > > > > Based on the sentence above, both of these are plausible orders: > > > > a. M, A, B, X, Z, Y, P, G > > > > b. M, A, X, Y, B, Z, P, G > > > > c. Maybe others too? > > > > * How does this relate to the dependency "mediation" algorithm > > maven uses when there are conflicting versions of a dependency requested? > > > > As far as I understand, that uses a breadth-first search, where the > > parent pom comes FIRST rather than last. > > > > Does that mean that mediation algorithm is basically unrelated to > > class path algorithm, or do they still have some things in common? > > > > E.g., ordering (a) above is also a breadth-first search, whereas (b) > > is depth-first. > > Any words of wisdom would be nice. > > > > Thanks, > > Mark. > > > > This message is for information purposes only. It is not a > > recommendation, advice, offer or solicitation to buy or sell a > > product or service, nor an official confirmation of any transaction. > > It is directed at persons who are professionals and is intended for > > the > > recipient(s) only. It is not directed at retail customers. 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